Maybe #Bluesky. I'm still kinda iffy about #centralized architectures like that. I guess it would be a good litmus test if they're willing to play nice or not.

There are technically bridges to Bluesky... I've even seen some content bleed over into Nostr occasionally. But I agree, Bluesky is decentralized "in theory", Mastodon and of course Nostr are much more decentralized "in fact."