Note how _getfinalpathname works and calling listdir on the final path name also works:

>>> os.symlink(".\\test", "Lib\\bar")
>>> os.listdir("Lib\\bar")[:4]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NotADirectoryError: [Error 267] The directory name is invalid: 'Lib\\bar\\*.*'

>>> nt._getfinalpathname("Lib\\bar")
'\\\\?\\C:\\t\\pathlib\\Lib\\test'
>>> os.listdir(nt._getfinalpathname("Lib\\bar"))[:4]
['185test.db', 'audiotest.au', 'autotest.py', 'badcert.pem']

Calling listdir on the non-final extended path doesn't work:

>>> os.listdir('\\\\?\\C:\\t\\pathlib\\Lib\\bar')[:4]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NotADirectoryError: [Error 267] The directory name is invalid: '\\\\?\\C:\\t\\pa
thlib\\Lib\\bar\\*.*'

But open() works:

>>> open('Lib\\bar\\regrtest.py')
<_io.TextIOWrapper name='Lib\\bar\\regrtest.py' mode='r' encoding='cp1252'>