@racchio I don't know much about #Nostr, other than that it's a fascist-run project with a disastrous cultural history. But yes, #Keet is for IM and runs fully decentralised.
(I'm going to use that word rather than "distributed" as the architecture *does* actually facilitate the distribution of power as well as of compute & storage. It's also built by a pretty cool community of anarchists & anarcho-syndicalists, at least the ones I've met.)