This is a 'big picture' issue but we should in general make sure that anywhere that accepts filenames/paths in astropy can accept pathlib.Path objects. This is in the standard library and is a very convenient way of defining file paths. A lot of parts of astropy should already work with this, but as @nstarman found there are still places where this is not the case (astropy/astropy-iers-data#1 (comment)).

Blocked by

• MNT: Run PTH flake test in prep for supporting pathlib #16924