Theoretically Hive can scale but that has yet to be actually proven.
Many underestimate the difficulty of scaling up.
It's always an ugly and ungraceful process.
As far as I know, NOSTR has no token and no reward mechanism other than Bitcoin tips via Lightning Network.
I think as time passed hive blockchain developers will experiment new things, As you know learning never ends I am very hopeful if it's possible to scales hive blockchain to millions of users we well find the way