One thing to keep in mind is that pkg_resources is a hodgepodge of functionality. We didn’t want to propagate that approach so we’ve been splitting up the relevant functionality into separate modules. importlib.metadata does part of the work, but so does importlib.resources. We intend for them both to support as much of the pkg_resources use cases as is feasible, so if there’s something missing, then please do file bugs either on Roundup or the individual project backport pages.
One thing we know is missing from importlib.resources is the ability to have a resource in a subdirectory of an imported package. That would require us to allow slashes in the resource names, just as pkg_resources does. Right now the requirement is that the resources must live in the package directory and that the package directory be importable. I actually tried to implement this but it’s more difficult than it seems, so I abandoned it and haven’t gotten back to it. Contributions welcome of course. 