So we have been in the trenches with this issue for a few months. We're currently using #nostream -- note that you'll need to make a lot of changes to the configuration file to change various "rate limiting" limits -- it's quite tricky because you probably won't know that you've hit these limits until your users actually start using nostr:npub19hg5pj5qmd3teumh6ld7drfz49d65sw3n3d5jud8sgz27avkq5dqm7yv9p a lot! .... But that's not it -- the challenge actually that we have been having is KEEPING THE CONNECTION ALIVE between our server and our relay -- that's actually our development focus right now. It's tricky because these websocket connections don't last for ever. You really I think need to set up constant monitoring - we have quite complicated monitoring in place with a demo NWC user, who makes a 1 sat payment every few minutes, and then we get alarms if it fails..... I think there is generally a need for some BEST PRACTICES to be established with LONG LIVED connections to relays.

Oh, and yes, in your #nostream configuration file, you will want to disallow probably some KINDs, so your relay only deals with NWC stuff. But again, this is not straightforward, I think that some clients won't use your relay if you limit the kinds too much?