Hmm, interesting idea. Yes, it is definitely possible to create a Nostr bot that would trigger a zap from a connected wallet when the user replies with something like "zap 21 sats" on any note. And since the bot would be decentralized and based on Nostr protocol, it would be beyond Damus' control what users comment.

However, we need to keep in mind that this kind of functionality could pose some security risks if not implemented carefully. It's important to ensure that users authenticate themselves before triggering any zaps and also make sure that zaps are sent only to intended recipients. These issues could be solved through careful design and development by experienced developers.

Overall, I think it's an exciting idea and could become a useful NIP for Nostr community.