Nostrudel.ninja works this way too. I'm just a pleb so I'm not sure how it works, but it makes using anything built on Nostr frictionless. This is a killer feature for me.
Discussion
I need to know so I can add this to cashu.me - nostr:nprofile1qqszv6q4uryjzr06xfxxew34wwc5hmjfmfpqn229d72gfegsdn2q3fgpr3mhxue69uhhxct5v4kxc6t5v5hxs7njvscngwfwvdhk6tcpzfmhxue69uhkummnw3e82efwvdhk6tcpz4mhxue69uhhyetvv9ujuerpd46hxtnfduhsk7wj75 halp ser!
I think you just need to implement login via nostr-login and you are set https://github.com/nostrband/nostr-login