Nitpick: Python strings are not "UTF-8"; they are abstract sequences of Unicode codepoints (and internally CPython stores UTF-32). However, UTF-8 is the default encoding for processing raw bytes received from the outside world and turning them into strings.

That said, I actually didn't realize that os.listdir() silently omits un-decodable entries, which I find mildly alarming. This behavior isn't mentioned in the docs (https://docs.python.org/3/library/os.html#os.listdir) and seems out-of-character for Python, which usually raises an exception by default if data cannot be decoded to text.

Are you sure that this is actually what happens with non-decodable filenames? Reading here (https://docs.python.org/3/glossary.html#term-filesystem-enco...) and here (https://docs.python.org/3/c-api/init_config.html#c.PyConfig....), it suggests that encoding errors should be handled by surrogate escapes by default on non-Windows systems.