diff --git a/dvc/config.py b/dvc/config.py
index c6323c2b7..c5d1fcdf2 100644
--- a/dvc/config.py
+++ b/dvc/config.py
@@ -99,6 +99,7 @@ class Config(dict):
     ):  # pylint: disable=super-init-not-called
         from dvc.fs import LocalFileSystem
 
+        dvc_dir = os.fspath(dvc_dir) if dvc_dir else None
         self.dvc_dir = dvc_dir
         self.wfs = LocalFileSystem()
         self.fs = fs or self.wfs
diff --git a/dvc/fs/dvc.py b/dvc/fs/dvc.py
index bdddc0693..2685dd438 100644
--- a/dvc/fs/dvc.py
+++ b/dvc/fs/dvc.py
@@ -139,7 +139,7 @@ class _DVCFileSystem(AbstractFileSystem):  # pylint:disable=abstract-method
             self.repo_factory = repo_factory
 
         def _getcwd():
-            relparts = ()
+            relparts: Tuple[str, ...] = ()
             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)
@@ -163,6 +163,7 @@ class _DVCFileSystem(AbstractFileSystem):  # pylint:disable=abstract-method
             self._datafss[key] = DataFileSystem(index=repo.index.data["repo"])
 
     def _get_key(self, path: "StrPath") -> Key:
+        path = os.fspath(path)
         parts = self.repo.fs.path.relparts(path, self.repo.root_dir)
         if parts == (os.curdir,):
             return ()
diff --git a/dvc/repo/brancher.py b/dvc/repo/brancher.py
index 75a8283fa..509ec0390 100644
--- a/dvc/repo/brancher.py
+++ b/dvc/repo/brancher.py
@@ -57,11 +57,11 @@ def brancher(  # noqa: E302
 
     from dvc.fs import LocalFileSystem
 
-    repo_root_parts = ()
+    repo_root_parts: Tuple[str, ...] = ()
     if self.fs.path.isin(self.root_dir, self.scm.root_dir):
         repo_root_parts = self.fs.path.relparts(self.root_dir, self.scm.root_dir)
 
-    cwd_parts = ()
+    cwd_parts: Tuple[str, ...] = ()
     if self.fs.path.isin(self.fs.path.getcwd(), self.scm.root_dir):
         cwd_parts = self.fs.path.relparts(self.fs.path.getcwd(), self.scm.root_dir)
 
@@ -144,11 +144,11 @@ def switch(repo: "Repo", rev: str) -> Iterator[str]:
     if rev != "workspace":
         rev = resolve_rev(repo.scm, rev)
 
-    repo_root_parts = ()
+    repo_root_parts: Tuple[str, ...] = ()
     if repo.fs.path.isin(repo.root_dir, repo.scm.root_dir):
         repo_root_parts = repo.fs.path.relparts(repo.root_dir, repo.scm.root_dir)
 
-    cwd_parts = ()
+    cwd_parts: Tuple[str, ...] = ()
     if repo.fs.path.isin(repo.fs.path.getcwd(), repo.scm.root_dir):
         cwd_parts = repo.fs.path.relparts(repo.fs.path.getcwd(), repo.scm.root_dir)
 
diff --git a/dvc/repo/checkout.py b/dvc/repo/checkout.py
index a722afd29..ef0988636 100644
--- a/dvc/repo/checkout.py
+++ b/dvc/repo/checkout.py
@@ -81,7 +81,7 @@ def _check_can_delete(
         if cache_fs.exists(cache_path):
             continue
 
-        entry_paths.append(fs.path.join(path, *entry.key))
+        entry_paths.append(fs.path.join(path, *(entry.key or ())))
 
     if not entry_paths:
         return
diff --git a/dvc/repo/plots/__init__.py b/dvc/repo/plots/__init__.py
index f37dec1cc..7fd0a47f7 100644
--- a/dvc/repo/plots/__init__.py
+++ b/dvc/repo/plots/__init__.py
@@ -446,6 +446,7 @@ def _resolve_definitions(
     definitions: "DictStrAny",
     onerror: Optional[Callable[[Any], Any]] = None,
 ):
+    config_path = os.fspath(config_path)
     config_dir = fs.path.dirname(config_path)
     result: Dict[str, Dict] = {}
     for plot_id, plot_props in definitions.items():