How to use the Ionic Service "User"?

I’m wondering if it is at all intended to make calls to the User service, or if this should only happen in the background through the Auth service.

The documentation seems to be not linked on, but it shows up in Google:

E.g. I’d like to load a specific user for testing purposes. (I also posted a question on stackoverflow regarding this:
Apparently I need to get an API token and set an authorization header, but I don’t know what the recommended way for approaching this is.

Perhaps I should refrain from using certain methods of the User class?