Device activity/screen time api

I have a request from a client that would like to create a solution where a central component is the ability to retrieve the users app usage. I can see that there are various api's todo that - one example is the Device Activity API. Another hope from the client is that this should be a web solution and not an app. I haven't quite been able to figure out if this is possible or not.

I have three questions:

  1. Is it possible to retrieve app usage information through a REST api (or similar) outside an iOS app?
  2. Is it possible to use the appleId as a kind of auth solution for a web application
  3. Are there any similar APIs for older versions than iOS 15?