We are almost done with a beta version of Routstr SDK (
https://github.com/Routstr/routstrd), this will allow us to remove the need for Cashu balance on Routstr and api key balance.
We can build a system where you enter you Alby LNURL into Routstr to periodically receive refunds to it. And when needed it'll automatically pull from your NWC. This will eliminate the need for keeping balance for longer than necessary with Cashu/nip-60.