@sun AP is a shitty implementation of a S2S event signaling protocol. Nostr isn't much better, as while NIP-01 is plain in meaning, reaching functional parity with established systems means reading and iterating on an actual (code) implementation based on scribbles in a dozen fragmented "proposals".
I pretty firmly believe that Nostr will eventually overtake AP, but not until a base spec is formalized and documented in a way that doesn't cater exclusively to amphetamine junkie bitcoin bros.