Chris on Nostr: I don't think there's any way to verify such a note is by a human. I.e. a bot could ...

I don't think there's any way to verify such a note is by a human. I.e. a bot could post a note saying it met a human or even another bot. Some form of PoW is required, e.g. requiring a micropayment to post a note or register for a relay.