Does the Auth module need to be expanded to support waitlists?

This is probably overly optimistic, but I want to limit new user signups with a waitlist, to manage registrations while new features are added and keep a cap on the expenses on traffic. My planned account registration path would go like this: New visitors have limited functionality in an anonymous mode. If they want to join the waitlist for access to all the features, they enter their email address. Once an administrator approves their access, an email with the magiclink is sent to them. If I disable user signups in Authentication - Settings, how can I still let users send their email addresses? It would seem the users database needs an "approved", "role", or ACL field for me to do this, correct? Also, magiclinks and related links need some backend logic to complete their tasks. I tried invoking the email validation link manually via a URL, but got a "no api key found in request" error. How do I implement this for a mobile app? I thought I wo…