2 years ago i was working on such idea to make a p2p overlay network over nostr for syncing. since no one paid attention i thought probably its a dumb idea and i stopped it.
more:
spec:
https://github.com/zurvan-lab/IPNNa repo which was intended to be the implementation (kind of empty repo):
https://github.com/zurvan-lab/redvinnote: you may see im using libp2p in my spec which is awful. back then i was obsessed with ipfs and these kind of stuff and i maid this mistake. if i start it again, it would be a custom protocol probably, much efficient and of course a working one.