To implement nip46 sign in simplest thing is nostr-login or nostr-ignition. Couple lines of code and your app can be signed into.

If you want to give new users your own nip05 you don't have to run the full nsec.app service - I can fire onAuth event on sign up and you can run users through your own onboarding and give them your own nip05. 

If you do want to host your own version of nsec.app I will have some instructions in readme soon.