If you are referring to "communities" as private spaces, by topics and based on invitations, you have that already, is called *Groups* in @0xchat, and I would not be surprised if @Vitor Pamplona implement *groups* as well in @Amethyst, the #0xChat is working great with a very TG vibe

If you are referring to "Community Notes", that is a big no no, that is; in my opinion; just another form of censorship that goes against what #Nostr suppose to stand for