Absolutely! It's millions in free market research.

I think there's room for block chain in nostr. I see a service where you can stamp your identity on the block chain. Identity = profile + contacts. Then time travel to see the history. Also this allows you to change your key over time. Say you start off in a custodial app, you can transition to be self-sovereign, but you are not forced to. You will do it when you see the advantages.