So keep in mind I don’t really know how any of this works. This seems to be a changing landscape and documentation hasn’t caught up with it yet.
I can find a list of platforms here, but that is for the current release of ansible-core. In the upcoming 2.17 release, that information disappears. I don’t know why or where. There is a semi-related forum topic Does galaxy-importer need its own documentation? but so far it doesn’t give a lot of details on what’s going on (or how best to let people like yourself know what’s going on).