If you use dunce::simplified(path) it will strip UNC only by manipulating the string, without accessing the disk, or even calling any Windows APIs....

Note that if I try to open such drive for example from my emacs editor, the same freeze happens, just as long.

No, this is not supported. This crate only trims \\C:\ paths.

It is likely a issue of the standard library since std::fs::canonicalize also failed to process such a mounted path.

Good point, this actually helps a lot! As you might be able to tell, I'm not super-familiar with UNC paths....

I think you could check if the path still starts with double slash.