I can definitely see a use case for supporting non-UTF-8 pathnames on disk (primarily for archaeological purposes). In a UTF-8-path-only world, what I would do

I can definitely see a use case for supporting non-UTF-8 pathnames on disk (primarily for archaeological purposes). In a UTF-8-path-only world, what I would do is have a mount option that says that the pathnames on disk are Latin-1 (so that \xff is mapped to U+00FF in UTF-8, which I'm too lazy to work its exact binary representation right now), and let the people doing archaeology on that write their own tools to remap the resulting mojibake pathnames into more readable ones. Not the cleanest solution, but there are ways to support non-UTF-8 disks even with UTF-8-only pathnames.