diff --git a/dvc/_debug.py b/dvc/_debug.py
index 4197619b2..63b6d9774 100644
--- a/dvc/_debug.py
+++ b/dvc/_debug.py
@@ -119,7 +119,7 @@ def debug():
         try:
             import ipdb as pdb  # noqa: T100, pylint: disable=import-error
         except ImportError:
-            import pdb  # noqa: T100
+            import pdb  # type: ignore[no-redef]  # noqa: T100
         pdb.post_mortem()
 
         raise  # prevent from jumping ahead
diff --git a/dvc/analytics.py b/dvc/analytics.py
index 3aa467bf0..7f196c02c 100644
--- a/dvc/analytics.py
+++ b/dvc/analytics.py
@@ -125,7 +125,7 @@ def _system_info():
     system = platform.system()
 
     if system == "Windows":
-        version = sys.getwindowsversion()
+        version = sys.getwindowsversion()  # type: ignore[attr-defined]
 
         return {
             "os": "windows",
diff --git a/dvc/api/data.py b/dvc/api/data.py
index a063612f1..a26885909 100644
--- a/dvc/api/data.py
+++ b/dvc/api/data.py
@@ -38,7 +38,11 @@ class _OpenContextManager(GCM):
         self, func, args, kwds
     ):  # pylint: disable=super-init-not-called
         self.gen = func(*args, **kwds)
-        self.func, self.args, self.kwds = func, args, kwds
+        self.func, self.args, self.kwds = (  # type: ignore[assignment]
+            func,
+            args,
+            kwds,
+        )
 
     def __getattr__(self, name):
         raise AttributeError(
diff --git a/dvc/api/params.py b/dvc/api/params.py
index 6cba9e98a..00c03f0d9 100644
--- a/dvc/api/params.py
+++ b/dvc/api/params.py
@@ -1,3 +1,4 @@
+import typing
 from collections import Counter
 from typing import Dict, Iterable, Optional, Union
 
@@ -242,11 +243,11 @@ def params_show(
         raise exception
 
     def _postprocess(params):
-        processed = {}
+        processed: Dict[str, Dict] = {}
         for rev, rev_data in params.items():
             processed[rev] = {}
 
-            counts = Counter()
+            counts: typing.Counter[str] = Counter()
             for file_data in rev_data["data"].values():
                 for k in file_data["data"]:
                     counts[k] += 1
diff --git a/dvc/cli/__init__.py b/dvc/cli/__init__.py
index 4d96e3ebf..b85a0dd9f 100644
--- a/dvc/cli/__init__.py
+++ b/dvc/cli/__init__.py
@@ -167,12 +167,12 @@ def main(argv=None):  # noqa: C901
         elif args.verbose == 1:
             level = logging.DEBUG
         elif args.verbose > 1:
-            level = logging.TRACE
+            level = logging.TRACE  # type: ignore[attr-defined]
 
         if level is not None:
             set_loggers_level(level)
 
-        logger.trace(args)
+        logger.trace(args)  # type: ignore[attr-defined]
 
         if not sys.stdout.closed and not args.quiet:
             from dvc.ui import ui
diff --git a/dvc/commands/data_sync.py b/dvc/commands/data_sync.py
index a8fad6468..3258a0b60 100644
--- a/dvc/commands/data_sync.py
+++ b/dvc/commands/data_sync.py
@@ -122,7 +122,7 @@ def shared_parent_parser():
             "Limit command scope to these tracked files/directories, "
             ".dvc files and stage names."
         ),
-    ).complete = completion.DVC_FILE
+    ).complete = completion.DVC_FILE  # type: ignore[attr-defined]
 
     return parent_parser
 
diff --git a/dvc/commands/experiments/show.py b/dvc/commands/experiments/show.py
index 208d3a347..4bb7a44f6 100644
--- a/dvc/commands/experiments/show.py
+++ b/dvc/commands/experiments/show.py
@@ -4,7 +4,7 @@ import os
 import re
 from collections import Counter, OrderedDict, defaultdict
 from datetime import date, datetime
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Any, Dict, Set
 
 from funcy import lmap
 
@@ -37,9 +37,9 @@ def _update_names(names, items):
 
 
 def _collect_names(all_experiments, **kwargs):
-    metric_names = defaultdict(dict)
-    param_names = defaultdict(dict)
-    deps_names = set()
+    metric_names: Dict[str, Dict[str, Any]] = defaultdict(dict)
+    param_names: Dict[str, Dict[str, Any]] = defaultdict(dict)
+    deps_names: Set[str] = set()
 
     for _, experiments in all_experiments.items():
         for exp_data in experiments.values():
@@ -328,7 +328,7 @@ def show_experiments(  # noqa: C901
 
     metric_names, param_names, deps_names = _collect_names(all_experiments)
 
-    headers = [
+    headers_list = [
         "Experiment",
         "rev",
         "typ",
@@ -340,13 +340,13 @@ def show_experiments(  # noqa: C901
 
     names = {**metric_names, **param_names}
     counter = Counter(flatten_list([list(a.keys()) for a in names.values()]))
-    counter.update(headers)
+    counter.update(headers_list)
     metric_headers = _normalize_headers(metric_names, counter)
     param_headers = _normalize_headers(param_names, counter)
 
     td = experiments_table(
         all_experiments,
-        headers,
+        headers_list,
         metric_headers,
         metric_names,
         param_headers,
diff --git a/dvc/commands/machine.py b/dvc/commands/machine.py
index c89f0ba30..a208e73f3 100644
--- a/dvc/commands/machine.py
+++ b/dvc/commands/machine.py
@@ -177,6 +177,7 @@ class CmdMachineRename(CmdBase):
             self._check_exists(conf)
             conf["machine"][self.args.new] = conf["machine"][self.args.name]
             try:
+                assert self.repo.machine
                 self.repo.machine.rename(self.args.name, self.args.new)
             except DvcException as error:
                 del conf["machine"][self.args.new]
diff --git a/dvc/commands/plots.py b/dvc/commands/plots.py
index 9451db875..71e3e5f0f 100644
--- a/dvc/commands/plots.py
+++ b/dvc/commands/plots.py
@@ -89,6 +89,7 @@ class CmdPlots(CmdBase):
                 "html_template", None
             )
             if html_template_path and not os.path.isabs(html_template_path):
+                assert self.repo.dvc_dir
                 html_template_path = os.path.join(
                     self.repo.dvc_dir, html_template_path
                 )
diff --git a/dvc/commands/stage.py b/dvc/commands/stage.py
index 6c3262bc8..85936d4fb 100644
--- a/dvc/commands/stage.py
+++ b/dvc/commands/stage.py
@@ -95,7 +95,7 @@ class CmdStageList(CmdBase):
 
         stages = self._get_stages()
         data = prepare_stages_data(stages, description=not self.args.name_only)
-        ui.table(data.items())
+        ui.table(list(data.items()))
 
         return 0
 
diff --git a/dvc/compare.py b/dvc/compare.py
index bbd19a406..d21b4d0db 100644
--- a/dvc/compare.py
+++ b/dvc/compare.py
@@ -328,8 +328,9 @@ def _format_field(
 ) -> str:
     def _format(_val):
         if isinstance(_val, float) and precision:
-            func = round if round_digits else _normalize_float
-            return func(_val, precision)
+            if round_digits:
+                return round(val, precision)
+            return _normalize_float(val, precision)
         if isinstance(_val, abc.Mapping):
             return {k: _format(v) for k, v in _val.items()}
         if isinstance(_val, list):
diff --git a/dvc/config.py b/dvc/config.py
index 2388c4d86..0e41f02a1 100644
--- a/dvc/config.py
+++ b/dvc/config.py
@@ -291,7 +291,7 @@ class Config(dict):
         return Schema(dirs_schema, extra=ALLOW_EXTRA)(conf)
 
     def load_config_to_level(self, level=None):
-        merged_conf = {}
+        merged_conf: Dict = {}
         for merge_level in self.LEVELS:
             if merge_level == level:
                 break
@@ -337,7 +337,7 @@ class Config(dict):
 
 
 def _parse_named(conf):
-    result = {"remote": {}, "machine": {}}
+    result: Dict[str, Dict] = {"remote": {}, "machine": {}}
 
     for section, val in conf.items():
         match = re_find(r'^\s*(remote|machine)\s*"(.*)"\s*$', section)
diff --git a/dvc/daemon.py b/dvc/daemon.py
index 50e0d82c8..5dfde30ae 100644
--- a/dvc/daemon.py
+++ b/dvc/daemon.py
@@ -25,21 +25,24 @@ def _popen(cmd, **kwargs):
 
 
 def _spawn_windows(cmd, env):
-    from subprocess import (
-        CREATE_NEW_PROCESS_GROUP,
-        CREATE_NO_WINDOW,
-        STARTF_USESHOWWINDOW,
-        STARTUPINFO,
-    )
+    if sys.platform == "win32":
+        from subprocess import (
+            CREATE_NEW_PROCESS_GROUP,
+            CREATE_NO_WINDOW,
+            STARTF_USESHOWWINDOW,
+            STARTUPINFO,
+        )
 
-    # https://stackoverflow.com/a/7006424
-    # https://bugs.python.org/issue41619
-    creationflags = CREATE_NEW_PROCESS_GROUP | CREATE_NO_WINDOW
+        # https://stackoverflow.com/a/7006424
+        # https://bugs.python.org/issue41619
+        creationflags = CREATE_NEW_PROCESS_GROUP | CREATE_NO_WINDOW
 
-    startupinfo = STARTUPINFO()
-    startupinfo.dwFlags |= STARTF_USESHOWWINDOW
+        startupinfo = STARTUPINFO()
+        startupinfo.dwFlags |= STARTF_USESHOWWINDOW
 
-    _popen(cmd, env=env, creationflags=creationflags, startupinfo=startupinfo)
+        _popen(
+            cmd, env=env, creationflags=creationflags, startupinfo=startupinfo
+        )
 
 
 def _spawn_posix(cmd, env):
diff --git a/dvc/dependency/__init__.py b/dvc/dependency/__init__.py
index 8c70bf878..965e75168 100644
--- a/dvc/dependency/__init__.py
+++ b/dvc/dependency/__init__.py
@@ -1,5 +1,5 @@
 from collections import defaultdict
-from typing import Any, Mapping
+from typing import Any, Mapping, Set
 
 from dvc.output import ARTIFACT_SCHEMA, DIR_FILES_SCHEMA, Output
 
@@ -59,7 +59,7 @@ def _merge_params(s_list):
     default_file = ParamsDependency.DEFAULT_PARAMS_FILE
 
     # figure out completely tracked params file, and ignore specific keys
-    wholly_tracked = set()
+    wholly_tracked: Set[str] = set()
     for key in s_list:
         if not isinstance(key, dict):
             continue
diff --git a/dvc/dependency/param.py b/dvc/dependency/param.py
index 10257f3bd..4b13b0cb6 100644
--- a/dvc/dependency/param.py
+++ b/dvc/dependency/param.py
@@ -104,7 +104,7 @@ class ParamsDependency(Dependency):
 
         from funcy import ldistinct
 
-        status = defaultdict(dict)
+        status: Dict[str, Any] = defaultdict(dict)
         info = self.hash_info.value if self.hash_info else {}
         actual = self.read_params()
 
@@ -165,7 +165,7 @@ class ParamsDependency(Dependency):
         if not self.exists:
             raise self.DoesNotExistError(self)
 
-        if not self.isfile and not self.isdir:
+        if not self.isfile() and not self.isdir():
             raise self.IsNotFileOrDirError(self)
 
         self.ignore()
diff --git a/dvc/dependency/repo.py b/dvc/dependency/repo.py
index 7013c71ba..fe19d4ec8 100644
--- a/dvc/dependency/repo.py
+++ b/dvc/dependency/repo.py
@@ -5,7 +5,6 @@ from typing import (
     TYPE_CHECKING,
     ContextManager,
     Dict,
-    Iterable,
     Optional,
     Set,
     Tuple,
@@ -169,7 +168,7 @@ class RepoDependency(Dependency):
             return used_obj_ids, meta, obj
 
     def _check_circular_import(
-        self, odb: "ObjectDB", obj_ids: Iterable[str]
+        self, odb: "ObjectDB", obj_ids: Set["HashInfo"]
     ) -> None:
         from dvc.exceptions import CircularImportError
         from dvc.fs.dvc import DVCFileSystem
diff --git a/dvc/external_repo.py b/dvc/external_repo.py
index b34032a93..de235ec4f 100644
--- a/dvc/external_repo.py
+++ b/dvc/external_repo.py
@@ -3,7 +3,7 @@ import os
 import tempfile
 import threading
 from contextlib import contextmanager
-from typing import TYPE_CHECKING, Collection, Dict, Iterator, Optional
+from typing import TYPE_CHECKING, Collection, Dict, Iterator, Optional, Tuple
 
 from funcy import retry, wrap_with
 
@@ -114,7 +114,7 @@ def erepo_factory(url, root_dir, cache_config):
     return make_repo
 
 
-CLONES: Dict[str, str] = {}
+CLONES: Dict[str, Tuple[str, bool]] = {}
 CACHE_DIRS: Dict[str, str] = {}
 
 
@@ -198,7 +198,7 @@ def _clone_default_branch(url, rev, for_write=False):  # noqa: C901
     """
     from scmrepo.git import Git
 
-    clone_path, shallow = CLONES.get(url, (None, False))
+    clone_path, shallow = CLONES.get(url) or (None, False)
 
     git = None
     try:
diff --git a/dvc/fs/dvc.py b/dvc/fs/dvc.py
index 165ce0984..b9e2af672 100644
--- a/dvc/fs/dvc.py
+++ b/dvc/fs/dvc.py
@@ -31,7 +31,7 @@ if TYPE_CHECKING:
 
 logger = logging.getLogger(__name__)
 
-RepoFactory = Union[Callable[[str], "Repo"], Type["Repo"]]
+RepoFactory = Union[Callable[..., "Repo"], Type["Repo"]]
 Key = Tuple[str, ...]
 
 
@@ -129,7 +129,7 @@ class _DVCFileSystem(AbstractFileSystem):  # pylint:disable=abstract-method
             repo = self._make_repo(
                 url=url, rev=rev, subrepos=subrepos, **repo_kwargs
             )
-            assert repo
+            assert repo is not None
             # pylint: disable=protected-access
             repo_factory = repo._fs_conf["repo_factory"]
 
@@ -142,6 +142,7 @@ class _DVCFileSystem(AbstractFileSystem):  # pylint:disable=abstract-method
 
         def _getcwd():
             relparts = ()
+            assert repo is not None
             if repo.fs.path.isin(repo.fs.path.getcwd(), repo.root_dir):
                 relparts = repo.fs.path.relparts(
                     repo.fs.path.getcwd(), repo.root_dir
@@ -182,8 +183,6 @@ class _DVCFileSystem(AbstractFileSystem):  # pylint:disable=abstract-method
 
     @property
     def repo_url(self):
-        if self.repo is None:
-            return None
         return self.repo.url
 
     @classmethod
diff --git a/dvc/lock.py b/dvc/lock.py
index 646188602..050c0d01a 100644
--- a/dvc/lock.py
+++ b/dvc/lock.py
@@ -131,6 +131,7 @@ class Lock(LockBase):
 
         if not self.is_locked:
             raise DvcException("Unlock called on an unlocked lock")
+        assert self._lock
         self._lock.close()
         self._lock = None
 
diff --git a/dvc/logger.py b/dvc/logger.py
index b48457533..f43475b1c 100644
--- a/dvc/logger.py
+++ b/dvc/logger.py
@@ -204,7 +204,7 @@ def disable_other_loggers():
     loggerDict = logging.root.manager.loggerDict  # pylint: disable=no-member
     for logger_name, logger in loggerDict.items():
         if logger_name != "dvc" and not logger_name.startswith("dvc."):
-            logger.disabled = True
+            logger.disabled = True  # type: ignore[union-attr]
 
 
 def set_loggers_level(level: int = logging.INFO) -> None:
diff --git a/dvc/output.py b/dvc/output.py
index d77b334fd..6122c5fdc 100644
--- a/dvc/output.py
+++ b/dvc/output.py
@@ -144,7 +144,7 @@ def _split_dict(d, keys):
 
 
 def _merge_data(s_list):
-    d = defaultdict(dict)
+    d: Dict[str, Dict] = defaultdict(dict)
     for key in s_list:
         if isinstance(key, str):
             d[key].update({})
@@ -316,7 +316,7 @@ class Output:
             and isinstance(stage.repo.fs, LocalFileSystem)
             and path_isin(path, stage.repo.root_dir)
         ):
-            self.def_path = relpath(path, stage.wdir)
+            self.def_path: str = relpath(path, stage.wdir)
             self.fs = stage.repo.fs
         else:
             self.def_path = path
diff --git a/dvc/parsing/context.py b/dvc/parsing/context.py
index 54046ba3b..f2c02fe81 100644
--- a/dvc/parsing/context.py
+++ b/dvc/parsing/context.py
@@ -306,7 +306,7 @@ class Context(CtxDict):
         """
         super().__init__(*args, **kwargs)
         self._track = False
-        self._tracked_data = defaultdict(dict)
+        self._tracked_data: Dict[str, Dict] = defaultdict(dict)
         self.imports = {}
         self._reserved_keys = {}
 
diff --git a/dvc/progress.py b/dvc/progress.py
index 13e7a5ca9..082c875bf 100644
--- a/dvc/progress.py
+++ b/dvc/progress.py
@@ -147,10 +147,16 @@ class Tqdm(tqdm):
     def format_dict(self):
         """inject `ncols_desc` to fill the display width (`ncols`)"""
         d = super().format_dict
-        ncols = d["ncols"] or 80
+        ncols: int = d["ncols"] or 80
         # assumes `bar_format` has max one of ("ncols_desc" & "ncols_info")
         ncols_left = (
-            ncols - len(self.format_meter(ncols_desc=1, ncols_info=1, **d)) + 1
+            ncols
+            - len(
+                self.format_meter(  # type: ignore[call-arg]
+                    ncols_desc=1, ncols_info=1, **d
+                )
+            )
+            + 1
         )
         ncols_left = max(ncols_left, 0)
         if ncols_left:
diff --git a/dvc/repo/__init__.py b/dvc/repo/__init__.py
index 69059dab4..9723918ff 100644
--- a/dvc/repo/__init__.py
+++ b/dvc/repo/__init__.py
@@ -244,9 +244,9 @@ class Repo:
 
             self._ignore()
 
-        self.metrics = Metrics(self)
+        self.metrics: Metrics = Metrics(self)
         self.plots: Plots = Plots(self)
-        self.params = Params(self)
+        self.params: Params = Params(self)
 
         self.stage_collection_error_handler: Optional[
             Callable[[str, Exception], None]
@@ -403,10 +403,11 @@ class Repo:
         return self.odb.repo.unprotect(target)
 
     def _ignore(self):
-        flist = [self.config.files["local"], self.tmp_dir]
-
+        flist = [self.config.files["local"]]
+        if tmp_dir := self.tmp_dir:
+            flist.append(tmp_dir)
         if path_isin(self.odb.repo.path, self.root_dir):
-            flist += [self.odb.repo.path]
+            flist.append(self.odb.repo.path)
 
         for file in flist:
             self.scm_context.ignore(file)
diff --git a/dvc/repo/checkout.py b/dvc/repo/checkout.py
index 88611b394..8e5db918e 100644
--- a/dvc/repo/checkout.py
+++ b/dvc/repo/checkout.py
@@ -1,6 +1,6 @@
 import logging
 import os
-from typing import TYPE_CHECKING, Set
+from typing import TYPE_CHECKING, Dict, List, Set
 
 from dvc.exceptions import (
     CheckoutError,
@@ -81,7 +81,12 @@ def checkout(
 ):
     from dvc.fs.callbacks import Callback
 
-    stats = {"added": [], "deleted": [], "modified": [], "failed": []}
+    stats: Dict[str, List[str]] = {
+        "added": [],
+        "deleted": [],
+        "modified": [],
+        "failed": [],
+    }
     if not targets:
         targets = [None]
         stats["deleted"] = _remove_unused_links(self)
diff --git a/dvc/repo/index.py b/dvc/repo/index.py
index 2c25c486d..2e1e6b99a 100644
--- a/dvc/repo/index.py
+++ b/dvc/repo/index.py
@@ -46,7 +46,9 @@ def log_walk(seq):
         start = time.perf_counter()
         yield root, dirs, files
         duration = format_time(time.perf_counter() - start)
-        logger.trace("%s in collecting stages from %s", duration, root)
+        logger.trace(  # type: ignore[attr-defined]
+            "%s in collecting stages from %s", duration, root
+        )
 
 
 def collect_files(
diff --git a/dvc/repo/plots/__init__.py b/dvc/repo/plots/__init__.py
index 3e69f9afb..ad89af4c7 100644
--- a/dvc/repo/plots/__init__.py
+++ b/dvc/repo/plots/__init__.py
@@ -605,7 +605,7 @@ def _load_sv(path, fs, delimiter=",", header=True):
             fieldnames=[str(i) for i in range(len(first_row))],
         )
 
-    fieldnames = reader.fieldnames
+    fieldnames = reader.fieldnames or []
     data = list(reader)
 
     return [
diff --git a/dvc/repo/reproduce.py b/dvc/repo/reproduce.py
index 37f1c0dd1..586087ab0 100644
--- a/dvc/repo/reproduce.py
+++ b/dvc/repo/reproduce.py
@@ -1,6 +1,6 @@
 import logging
 from functools import partial
-from typing import TYPE_CHECKING, Iterator
+from typing import TYPE_CHECKING, Iterator, List
 
 from dvc.exceptions import DvcException, ReproductionError
 from dvc.repo.scm_context import scm_context
@@ -16,7 +16,7 @@ if TYPE_CHECKING:
 logger = logging.getLogger(__name__)
 
 
-def _reproduce_stage(stage: "Stage", **kwargs):
+def _reproduce_stage(stage: "Stage", **kwargs) -> List["Stage"]:
     def _run_callback(repro_callback):
         stage.dump(update_pipeline=False)
         _track_stage(stage)
@@ -173,9 +173,9 @@ def _reproduce_stages(  # noqa: C901
 
     force_downstream = kwargs.pop("force_downstream", False)
     result = []
-    unchanged = []
+    unchanged: List["Stage"] = []
     # `ret` is used to add a cosmetic newline.
-    ret = []
+    ret: List["Stage"] = []
     checkpoint_func = kwargs.pop("checkpoint_func", None)
 
     for i, stage in enumerate(steps):
@@ -234,7 +234,7 @@ def _get_steps(G, stages, downstream, single_item):
                 # NOTE: disconnect frozen stage from its dependencies
                 active.remove_edges_from(G.out_edges(stage))
 
-    all_pipelines = []
+    all_pipelines: List["Stage"] = []
     for stage in stages:
         if downstream:
             # NOTE (py3 only):
diff --git a/dvc/stage/cache.py b/dvc/stage/cache.py
index 7362c48cf..31e3cc59b 100644
--- a/dvc/stage/cache.py
+++ b/dvc/stage/cache.py
@@ -2,7 +2,7 @@ import logging
 import os
 import tempfile
 from contextlib import contextmanager
-from typing import TYPE_CHECKING, Optional
+from typing import TYPE_CHECKING, List, Optional, Tuple
 
 from funcy import first
 
@@ -236,7 +236,7 @@ class StageCache:
             message = f"run-cache is not supported for http filesystem: {path}"
             raise RunCacheNotSupported(message)
 
-        ret = []
+        ret: List[Tuple[str, str]] = []
         if not from_fs.exists(runs):
             return ret
 
diff --git a/dvc/stage/loader.py b/dvc/stage/loader.py
index 0ea7ce694..e71e5779b 100644
--- a/dvc/stage/loader.py
+++ b/dvc/stage/loader.py
@@ -200,7 +200,10 @@ class SingleStageLoader(Mapping):
 
     @classmethod
     def load_stage(
-        cls, dvcfile: "SingleStageFile", d: Dict[str, Any], stage_text: str
+        cls,
+        dvcfile: "SingleStageFile",
+        d: Dict[str, Any],
+        stage_text: Optional[str],
     ) -> Stage:
         path, wdir = resolve_paths(
             dvcfile.repo.fs, dvcfile.path, d.get(Stage.PARAM_WDIR)
diff --git a/dvc/stage/serialize.py b/dvc/stage/serialize.py
index b37eb4193..686b302d0 100644
--- a/dvc/stage/serialize.py
+++ b/dvc/stage/serialize.py
@@ -1,7 +1,14 @@
 from collections import OrderedDict
-from functools import partial
 from operator import attrgetter
-from typing import TYPE_CHECKING, List, no_type_check
+from typing import (
+    TYPE_CHECKING,
+    Dict,
+    Iterable,
+    List,
+    Optional,
+    Union,
+    no_type_check,
+)
 
 from funcy import post_processing
 
@@ -34,9 +41,6 @@ PARAM_PUSH = Output.PARAM_PUSH
 DEFAULT_PARAMS_FILE = ParamsDependency.DEFAULT_PARAMS_FILE
 
 
-sort_by_path = partial(sorted, key=attrgetter("def_path"))
-
-
 @post_processing(OrderedDict)
 def _get_flags(out):
     annot = out.annot.to_dict()
@@ -67,7 +71,7 @@ def _serialize_out(out):
 @no_type_check
 def _serialize_outs(outputs: List[Output]):
     outs, metrics, plots = [], [], []
-    for out in sort_by_path(outputs):
+    for out in sorted(outputs, key=attrgetter("def_path")):
         bucket = outs
         if out.plot:
             bucket = plots
@@ -77,7 +81,7 @@ def _serialize_outs(outputs: List[Output]):
     return outs, metrics, plots
 
 
-def _serialize_params_keys(params):
+def _serialize_params_keys(params: Iterable["ParamsDependency"]):
     """
     Returns the following format of data:
      ['lr', 'train', {'params2.yaml': ['lr']}]
@@ -86,12 +90,12 @@ def _serialize_params_keys(params):
     at the first, and then followed by entry of other files in lexicographic
     order. The keys of those custom files are also sorted in the same order.
     """
-    keys = []
-    for param_dep in sort_by_path(params):
+    keys: List[Union[str, Dict[str, Optional[List[str]]]]] = []
+    for param_dep in sorted(params, key=attrgetter("def_path")):
         # when on no_exec, params are not filled and are saved as list
-        k = sorted(param_dep.params)
+        k: List[str] = sorted(param_dep.params)
         if k and param_dep.def_path == DEFAULT_PARAMS_FILE:
-            keys = k + keys
+            keys = k + keys  # type: ignore[operator,assignment]
         else:
             keys.append({param_dep.def_path: k or None})
     return keys
@@ -106,7 +110,7 @@ def _serialize_params_values(params: List[ParamsDependency]):
     alphabetical order. The param values are sorted too(not recursively though)
     """
     key_vals = OrderedDict()
-    for param_dep in sort_by_path(params):
+    for param_dep in sorted(params, key=attrgetter("def_path")):
         dump = param_dep.dumpd()
         path, params = dump[PARAM_PATH], dump[PARAM_PARAMS]
         if isinstance(params, dict):
@@ -119,9 +123,9 @@ def _serialize_params_values(params: List[ParamsDependency]):
 
 def to_pipeline_file(stage: "PipelineStage"):
     wdir = resolve_wdir(stage.wdir, stage.path)
-    params, deps = split_params_deps(stage)
-    deps = sorted(d.def_path for d in deps)
-    params = _serialize_params_keys(params)
+    param_objs, deps_objs = split_params_deps(stage)
+    deps = sorted(d.def_path for d in deps_objs)
+    params = _serialize_params_keys(param_objs)
 
     outs, metrics, plots = _serialize_outs(stage.outs)
 
@@ -172,7 +176,7 @@ def to_single_stage_lockfile(stage: "Stage", **kwargs) -> dict:
     res = OrderedDict([("cmd", stage.cmd)])
     params, deps = split_params_deps(stage)
     deps, outs = (
-        [_dumpd(item) for item in sort_by_path(items)]
+        [_dumpd(item) for item in sorted(items, key=attrgetter("def_path"))]
         for items in [deps, stage.outs]
     )
     params = _serialize_params_values(params)
diff --git a/dvc/testing/fixtures.py b/dvc/testing/fixtures.py
index ee6b00344..d2cce3489 100644
--- a/dvc/testing/fixtures.py
+++ b/dvc/testing/fixtures.py
@@ -46,6 +46,8 @@ def make_tmp_dir(tmp_path_factory, request, worker_id):
             cache_dir = tmp_path_factory.mktemp("dvc-test-cache" + worker_id)
             TmpDir(cache_dir).init(scm=scm, dvc=dvc, subdir=subdir)
             CACHE[(scm, dvc, subdir)] = cache = os.fspath(cache_dir)
+
+        assert cache
         path = tmp_path_factory.mktemp(name) if isinstance(name, str) else name
 
         # ignore sqlite files from .dvc/tmp. We might not be closing the cache
diff --git a/dvc/testing/path_info.py b/dvc/testing/path_info.py
index 93f698a73..d3a4291dc 100644
--- a/dvc/testing/path_info.py
+++ b/dvc/testing/path_info.py
@@ -12,13 +12,14 @@ from dvc.utils.objects import cached_property
 class _BasePath:
     def overlaps(self, other):
         if isinstance(other, (str, bytes)):
-            other = self.__class__(other)
+            other = self.__class__(other)  # type: ignore[call-arg]
         elif self.__class__ != other.__class__:
             return False
         return self.isin_or_eq(other) or other.isin(self)
 
     def isin_or_eq(self, other):
-        return self == other or self.isin(other)  # pylint: disable=no-member
+        # pylint: disable-next=no-member
+        return self == other or self.isin(other)  # type: ignore[attr-defined]
 
 
 class PathInfo(pathlib.PurePath, _BasePath):
@@ -35,10 +36,11 @@ class PathInfo(pathlib.PurePath, _BasePath):
                 WindowsPathInfo if os.name == "nt" else PosixPathInfo
             )
 
-        return cls._from_parts(args)
+        return cls._from_parts(args)  # type: ignore[attr-defined]
 
     def as_posix(self):
-        f = self._flavour  # pylint: disable=no-member
+        # pylint: disable-next=no-member
+        f = self._flavour  # type: ignore[attr-defined]
         # Unlike original implementation [1] that uses `str()` we actually need
         # to use `fspath`, because we've overridden `__str__` method to return
         # relative paths, which will break original `as_posix`.
@@ -75,7 +77,10 @@ class PathInfo(pathlib.PurePath, _BasePath):
             return False
         # Use cached casefolded parts to compare paths
         n = len(other._cparts)
-        return len(self._cparts) > n and self._cparts[:n] == other._cparts
+        return (
+            len(self._cparts) > n  # type: ignore[attr-defined]
+            and self._cparts[:n] == other._cparts  # type: ignore[attr-defined]
+        )
 
     def relative_to(self, other):  # pylint: disable=arguments-differ
         # pathlib relative_to raises exception when one path is not a direct
@@ -153,7 +158,7 @@ class URLInfo(_BasePath):
             self._path = path
         else:
             if path and path[0] != "/":
-                path = "/" + path
+                path = "/" + path  # type: ignore[operator]
             self._spath = path
 
     @property
@@ -165,7 +170,9 @@ class URLInfo(_BasePath):
         return self._base_parts + self._path.parts
 
     def replace(self, path=None):
-        return self.from_parts(*self._base_parts, path=path)
+        return self.from_parts(  # type: ignore[misc]
+            *self._base_parts, path=path
+        )
 
     @cached_property
     def url(self) -> str:
@@ -271,7 +278,7 @@ class HTTPURLInfo(URLInfo):
         self.fragment = p.fragment
 
     def replace(self, path=None):
-        return self.from_parts(
+        return self.from_parts(  # type: ignore[misc]
             *self._base_parts,
             params=self.params,
             query=self.query,
diff --git a/dvc/testing/tmp_dir.py b/dvc/testing/tmp_dir.py
index eca2a19e0..490c5abe3 100644
--- a/dvc/testing/tmp_dir.py
+++ b/dvc/testing/tmp_dir.py
@@ -76,9 +76,8 @@ class TmpDir(pathlib.Path):
             )
         # init parameter and `_init` method has been removed in Python 3.10.
         kw = {"init": False} if sys.version_info < (3, 10) else {}
-        self = cls._from_parts(  # pylint: disable=unexpected-keyword-arg
-            args, **kw
-        )
+        # pylint: disable-next=unexpected-keyword-arg
+        self = cls._from_parts(args, **kw)  # type: ignore[attr-defined]
         if not self._flavour.is_supported:
             raise NotImplementedError(
                 f"cannot instantiate {cls.__name__!r} on your system"
@@ -236,7 +235,8 @@ class TmpDir(pathlib.Path):
                 path.name: path.read_text(*args, **kwargs)
                 for path in self.iterdir()
             }
-        return super().read_text(*args, encoding="utf-8", **kwargs)
+        kwargs.setdefault("encoding", "utf-8")  # type: ignore[call-overload]
+        return super().read_text(*args, **kwargs)
 
     def oid_to_path(self, hash_):
         return str(self / hash_[0:2] / hash_[2:])
diff --git a/dvc/testing/workspace_tests.py b/dvc/testing/workspace_tests.py
index ac81074ff..a16b3b7c7 100644
--- a/dvc/testing/workspace_tests.py
+++ b/dvc/testing/workspace_tests.py
@@ -1,4 +1,5 @@
 import os
+from typing import Dict, Union
 
 import pytest
 
@@ -74,7 +75,7 @@ class TestImport:
         # of directories. So instead we create an empty file that ends with a
         # trailing slash in order to actually support this operation
         if is_object_storage:
-            contents = ""
+            contents: Union[str, Dict[str, str]] = ""
         else:
             contents = {}
 
diff --git a/dvc/utils/collections.py b/dvc/utils/collections.py
index f22af3b55..23350813f 100644
--- a/dvc/utils/collections.py
+++ b/dvc/utils/collections.py
@@ -1,9 +1,18 @@
 import inspect
 from collections.abc import Mapping
 from functools import wraps
-from typing import Callable, Dict, Iterable, List, TypeVar, Union
+from typing import (
+    Callable,
+    Dict,
+    Iterable,
+    List,
+    TypeVar,
+    Union,
+    no_type_check,
+)
 
 
+@no_type_check
 def apply_diff(src, dest):  # noqa: C901
     """Recursively apply changes from src to dest.
 
@@ -155,7 +164,9 @@ def validate(*validators: Callable, post: bool = False):
         def inner(*args, **kwargs):
             ba = sig.bind(*args, **kwargs)
             ba.apply_defaults()
-            ba.arguments = _NamespacedDict(ba.arguments)
+            ba.arguments = _NamespacedDict(  # type: ignore[assignment]
+                ba.arguments
+            )
 
             if not post:
                 for validator in validators:
diff --git a/dvc/utils/diff.py b/dvc/utils/diff.py
index 48f246a5c..269bf31a7 100644
--- a/dvc/utils/diff.py
+++ b/dvc/utils/diff.py
@@ -1,5 +1,6 @@
 import json
 from collections import defaultdict
+from typing import Dict
 
 from .flatten import flatten
 
@@ -46,7 +47,7 @@ def _diff_dicts(old_dict, new_dict, with_unchanged):
     new = _flatten(new_dict)
     old = _flatten(old_dict)
 
-    res = defaultdict(dict)
+    res: Dict[str, Dict] = defaultdict(dict)
 
     xpaths = set(old.keys())
     xpaths.update(set(new.keys()))
@@ -77,7 +78,7 @@ def diff(old, new, with_unchanged=False):
     paths = set(old.keys())
     paths.update(set(new.keys()))
 
-    res = defaultdict(dict)
+    res: Dict[str, Dict] = defaultdict(dict)
     for path in paths:
         path_diff = _diff(
             old.get(path, {}).get("data", {}),
diff --git a/dvc/utils/serialize/_common.py b/dvc/utils/serialize/_common.py
index 349d74593..e955c3bb0 100644
--- a/dvc/utils/serialize/_common.py
+++ b/dvc/utils/serialize/_common.py
@@ -9,6 +9,7 @@ from typing import (
     Dict,
     Optional,
     Protocol,
+    TextIO,
     Union,
 )
 
@@ -28,6 +29,11 @@ class DumperFn(Protocol):
         ...
 
 
+class DumpersFn(Protocol):
+    def __call__(self, data: Any, stream: TextIO) -> Any:
+        ...
+
+
 class ModifierFn(Protocol):
     def __call__(
         self, path: "StrPath", fs: Optional["FileSystem"] = None
@@ -78,7 +84,7 @@ def _load_data(
 def _dump_data(
     path,
     data: Any,
-    dumper: DumperFn,
+    dumper: DumpersFn,
     fs: Optional["FileSystem"] = None,
     **dumper_args,
 ):
@@ -91,11 +97,11 @@ def _dump_data(
 def _modify_data(
     path: "StrPath",
     parser: ParserFn,
-    dumper: DumperFn,
+    dumper: DumpersFn,
     fs: Optional["FileSystem"] = None,
 ):
     exists_fn = fs.exists if fs else os.path.exists
     file_exists = exists_fn(path)
     data = _load_data(path, parser=parser, fs=fs) if file_exists else {}
     yield data
-    dumper(path, data, fs=fs)
+    _dump_data(path, data, dumper=dumper, fs=fs)
diff --git a/dvc/utils/serialize/_json.py b/dvc/utils/serialize/_json.py
index ee2a9ce49..c6e9ac231 100644
--- a/dvc/utils/serialize/_json.py
+++ b/dvc/utils/serialize/_json.py
@@ -19,13 +19,17 @@ def parse_json(text, path, **kwargs):
         return json.loads(text, **kwargs) or {}
 
 
+def _dump_json(data, stream, **kwargs):
+    return json.dump(data, stream, **kwargs)
+
+
 def dump_json(path, data, fs=None, **kwargs):
-    return _dump_data(path, data, dumper=json.dump, fs=fs, **kwargs)
+    return _dump_data(path, data, dumper=_dump_json, fs=fs, **kwargs)
 
 
 @contextmanager
 def modify_json(path, fs=None):
-    with _modify_data(path, parse_json, dump_json, fs=fs) as d:
+    with _modify_data(path, parse_json, _dump_json, fs=fs) as d:
         yield d
 
 
diff --git a/dvc/utils/serialize/_py.py b/dvc/utils/serialize/_py.py
index ea6d9f1ca..945410d8e 100644
--- a/dvc/utils/serialize/_py.py
+++ b/dvc/utils/serialize/_py.py
@@ -1,5 +1,6 @@
 import ast
 from contextlib import contextmanager
+from typing import Any
 
 from funcy import reraise
 
@@ -81,7 +82,7 @@ def dump_py(path, data, fs=None):
 
 @contextmanager
 def modify_py(path, fs=None):
-    with _modify_data(path, parse_py_for_update, dump_py, fs=fs) as d:
+    with _modify_data(path, parse_py_for_update, _dump, fs=fs) as d:
         yield d
 
 
@@ -129,16 +130,18 @@ def _ast_assign_to_dict(assign, only_self_params=False, lineno=False):
     else:
         raise AttributeError
 
+    value: Any
     if isinstance(assign.value, ast.Dict):
         value = {}
         for key, val in zip(assign.value.keys, assign.value.values):
             if lineno:
-                value[ast.literal_eval(key)] = {
+                value[ast.literal_eval(key)] = {  # type: ignore[arg-type]
                     "lineno": assign.lineno - 1,
                     "value": ast.literal_eval(val),
                 }
             else:
-                value[ast.literal_eval(key)] = ast.literal_eval(val)
+                v = ast.literal_eval(val)
+                value[ast.literal_eval(key)] = v  # type: ignore[arg-type]
     elif isinstance(assign.value, ast.List):
         value = [ast.literal_eval(val) for val in assign.value.elts]
     elif isinstance(assign.value, ast.Set):
diff --git a/dvc/utils/serialize/_toml.py b/dvc/utils/serialize/_toml.py
index 31313896a..1d21ae4ff 100644
--- a/dvc/utils/serialize/_toml.py
+++ b/dvc/utils/serialize/_toml.py
@@ -47,5 +47,5 @@ def dump_toml(path, data, fs=None, **kwargs):
 
 @contextmanager
 def modify_toml(path, fs=None):
-    with _modify_data(path, parse_toml_for_update, dump_toml, fs=fs) as d:
+    with _modify_data(path, parse_toml_for_update, _dump, fs=fs) as d:
         yield d
diff --git a/dvc/utils/serialize/_yaml.py b/dvc/utils/serialize/_yaml.py
index 12e0b70a4..b8c4a55e0 100644
--- a/dvc/utils/serialize/_yaml.py
+++ b/dvc/utils/serialize/_yaml.py
@@ -1,6 +1,7 @@
 import io
 from collections import OrderedDict
 from contextlib import contextmanager
+from typing import Any, TextIO
 
 from funcy import reraise
 
@@ -53,7 +54,7 @@ def _get_yaml():
     return yaml
 
 
-def _dump(data, stream):
+def _dump(data: Any, stream: TextIO) -> Any:
     yaml = _get_yaml()
     return yaml.dump(data, stream)
 
@@ -76,5 +77,5 @@ def dumps_yaml(d):
 
 @contextmanager
 def modify_yaml(path, fs=None):
-    with _modify_data(path, parse_yaml_for_update, dump_yaml, fs=fs) as d:
+    with _modify_data(path, parse_yaml_for_update, _dump, fs=fs) as d:
         yield d
diff --git a/dvc/utils/threadpool.py b/dvc/utils/threadpool.py
index 97de574d8..e621c05a5 100644
--- a/dvc/utils/threadpool.py
+++ b/dvc/utils/threadpool.py
@@ -45,29 +45,29 @@ class ThreadPoolExecutor(futures.ThreadPoolExecutor):
             tasks.update(create_taskset(len(done)))
 
     def shutdown(self, wait=True, *, cancel_futures=False):
-        if sys.version_info > (3, 9):
+        if sys.version_info > (3, 9):  # pylint: disable=no-else-return
             # pylint: disable=unexpected-keyword-arg
             return super().shutdown(wait=wait, cancel_futures=cancel_futures)
+        else:
+            with self._shutdown_lock:
+                self._shutdown = True
+                if cancel_futures:
+                    # Drain all work items from the queue, and then cancel
+                    # their associated futures.
+                    while True:
+                        try:
+                            work_item = self._work_queue.get_nowait()
+                        except queue.Empty:
+                            break
+                        if work_item is not None:
+                            work_item.future.cancel()
 
-        with self._shutdown_lock:
-            self._shutdown = True
-            if cancel_futures:
-                # Drain all work items from the queue, and then cancel their
-                # associated futures.
-                while True:
-                    try:
-                        work_item = self._work_queue.get_nowait()
-                    except queue.Empty:
-                        break
-                    if work_item is not None:
-                        work_item.future.cancel()
-
-            # Send a wake-up to prevent threads calling
-            # _work_queue.get(block=True) from permanently blocking.
-            self._work_queue.put(None)
-        if wait:
-            for t in self._threads:
-                t.join()
+                # Send a wake-up to prevent threads calling
+                # _work_queue.get(block=True) from permanently blocking.
+                self._work_queue.put(None)  # type: ignore[arg-type]
+            if wait:
+                for t in self._threads:
+                    t.join()
 
     def __exit__(self, exc_type, exc_val, exc_tb):
         if self._cancel_on_error:
diff --git a/pyproject.toml b/pyproject.toml
index 873e862ce..567ff1ed7 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -226,7 +226,7 @@ show_error_context = true
 show_traceback = true
 pretty = true
 no_implicit_optional = true
-check_untyped_defs = false
+check_untyped_defs = true
 strict_equality = true
 strict_concatenate = true
 # Warnings