But then you have all the same federation politics and drama at the community level like we do at the instance level. It’d be such a mess.
Just make it easier for users to subscribe to each instance of a community with one tap. And let them view them all grouped in one feed.
And better yet, let people combine any communities together into a personal group; not just ones with the same name. There’s no need to get mods involved at all. I wrote more about this in another comment.