Self register with Customer ID

Hello,

I have a rather specific need for an app.
I want to record a list of customer IDs to my Nextcloud, users should then be able to self-register themselves with their customer ID and should be asked for their full name and e-mail address during registration. If the customer ID is not in the recorded list, self-registration should be denied.

Is there an app for this? Or could someone potentially develop such an app?

I’d be very grateful if someone could help me on this!