Actually even better would be for nostr:npub1ex7mdykw786qxvmtuls208uyxmn0hse95rfwsarvfde5yg6wy7jq6qvyt9 — if it hasn’t already — to let you spend fiat and convert to BTC instantaneously (but not convert back to another currency) and send to the merchant. That way, you spent only fiat, but the recipient got BTC via nostr:npub1ex7mdykw786qxvmtuls208uyxmn0hse95rfwsarvfde5yg6wy7jq6qvyt9, and you are not even engaging in a taxable transaction at all.