So it looks like some Scuttlebutt folks have made a new protocol called PZP (previously PPPPP, which was a better name) and they even have a section in their docs about Nostr: https://pzp.wiki/guide/intro/#how-pzp-is-different-from-nostr
But aside from that the protocol seems to be pretty much like SSB, but with per-device keys and no strict need for a key to follow a single chain of notes. I can only imagine this makes the implementation much harder.
Do you have opinions @rabble @npub16zsl...92l7?