Using the Apple Login, the user can choose to disclose the email address or a private address. Nothing else comes through (at least with Adalo). Note you can still communicate with the user via email using the private address. You need to set your allowed email domains in the Apple settings. Apple will relay the message. Here’s some info:
Apple seems to state that the name passes, but not in my experience.
When a user creates a new account, I have a field in the database called UserType. When they first login, it will be blank, so on my home screen, I have a page that checks for field UserType = Blank and then welcomes the new user and asks them to complete their profile. This page also sets their user type to “User” so now I know they completed this step.