I’m surprised a P2P exchange hasn’t been built on it already like robosats, bisq, etc.
Discussion
You could probably do that with NIP-15 already but pure P2P is pretty scary if you don't know the other party. Could be easy to scam someone without a trusted custodian in the middle of the trade.
Planning on building out a P2P exchange on top of nostr:npub15dc33fyg3cpd9r58vlqge2hh8dy6hkkrjxkhluv2xpyfreqkmsesesyv6e; some sort of escrow system is the first step.