Cashu.me implemented the NWC but is still in LN. nostr:npub1tm99pgz2lth724jeld6gzz6zv48zy6xp4n9xu5uqrwvx9km54qaqkkxn72 I think is a good model that implements zaps in Ecash, claims it with an anonymous address in npub.cash directly to your wallet in the messaging app.