Interesting you mention badges. First, aren't those client-specific? (I'm really not sure.) If so, that wouldn't work as an NFT...the whole point of an NFT is that it is unique (U) and if each client did their own thing...not unique.
Also, the (O) of ownership would be a problem in my mind. Though I don't know how badges work on Nostr, my guess is that they are assigned to me (like an airdrop?). But, as such, I can't transfer them away from my "account".
Anyway, the reason I say it's interesting is that I kind of had a discussion on this on badges on the Hive blockchain...are badges really NFTs?
Appreciate the idea.