Sorry. I'm asking through a 3rd party - this is not my area of expertise.
We're looking for REST API in order to build a separate App in the future.
We will want pretty much the whole user profile integrated, All fields.
I'm not sure yet about GJ Groups, but possibly them also.
I was asked this: "If you can figure out and create an example of how login can be done via POST request, and data retrieval via GET request, that would be helpful."