Nice Had a similar idea a while ago but didn't get around to implement it yet. https://git.nostrdev.com/freakoverse/DNN/src/branch/main/… Though working on different assumptions than what you've build. instead of having an npub publish a SP address, no one does anything, the sender derives an bitcoin address (or any secp256k1-based crypto) from the receiver's npub and sends to him and then notifies him via a nostr event.