While I frequently advocate on the side of "not every 3-line function needs to be in the stdlib", there are a lot of convenience functions for Unix in the stdlib (reflecting the fact that Python was initially developed on Unix) and having them for Windows as well seems only fair. Given the existence of pathlib.Path.is_fifo(), I think it's reasonable to include is_junction() too. (There's no isfifo() in os.path, though, so the argument for os.path.isjunction() is correspondingly weaker).

Paul