Bluesky's ATprotocol has implemented OAuth to enable new apps to use your identity via their hosted PDS identity server. Basically this is what you'd need to do in order to just get started building a Bluesky app... It's not easy and developer friendly the way Nostr is.... it's so complicated there are sold out 'masterclass' paid courses to just be able to login and sign events!

https://ti.to/ngerakines/atprotocol-oauth-masterclass-fall-2025