I have so many questions for you! I was able to create a proof of concept, but would love to know some of the missing details. The current documentation is not complete enough to make a working app, I had to guess things based on my knowledge of OIDC.
developer.okta.com/blog/2019…
Yes it seems to be designed for authentication only. They do also return an OAuth access token and refresh, though I am not sure what you can do with that yet.
In contrast: this forces app developers to provide users the choice between Apple or some other sign-in, rather than letting developers require just e.g. Facebook login.
More: aaronparecki.com/2019/06/04/…
Anyway, if you're curious about what this will look like, I wrote a sample app that uses Sign In with Apple so you can see how it works.
developer.okta.com/blog/2019…
Will we see other OAuth providers follow suit and start randomizing email addresses and user IDs returned to apps? I hope so!
Ironically, Facebook first started doing this a few years ago when they launched app-scoped user IDs.
Is Apple using their position as gatekeepers of the App Store to force adoption of "Sign In with Apple"?
Yes.
Is this a bad thing?
No.
Does this affect you if you don't use an iOS device?
No.
Does this benefit people who have an iOS device?
Yes.
At the end of the day, the benefit of signing in to apps is to be able to save stuff to your account so you can restore it later, and to get email notifications.
Yes, this is a little additional work for app developers to support another OAuth provider, but is really not that different from supporting both Twitter and Facebook, or Snapchat and Instagram.