Seriously this is one of the things I enjoy doing; connecting ideas across communities.

I had luck with Range-Based-Set-Reconciliation/Negentropy (I guess because people trusted Strfry developer, fair enough), not much with the rest of my suggestions :D

Nostr is not special, anything that people tried for local first and set reconciliation and "bring your own background" etc. applies to Nostr and any open web protocol.

Fun fact, Peergos is based on Cryptree which was developed like 15 years ago.

There are very few new ideas, just ego preventing us from using old ones.