NWC does not require a custodian. I opted for using custodians in Bankify because it's useful in some of my experiments and workshops to display a basic wallet interface that "just works" right away, with send and receive already enabled from the get-go, and an easy API to hook it up to some of my other apps (and third party apps like Stacker News). Ecash mints are probably the best available solution right now for that specific problem. But enabling NWC for more self custodial wallets is on my to-do list.