See you need a NIP60 wallet so that the user’s balance can viewed across clients But then you need a lightning address so that you’re interoperable with other clients so then you get a npub.cash address But users don’t want to run their own server for a lightning address or their own mint to hold funds so then you need a bitcoin address for self custody tied to their npub But then you need the ecash wallet to transfer from a mint to self-custody so you need a Submarine Swap using Boltz.exchange sdk And that’s how you get self-custody zaps without running a node