The old version you mention is still correct for several endpoints. The differences being that now the Quiz, Question, QuizProps and QuizQuestion, Response and Schedule endpoints no longer exist - these were basically there for the course publication process from Moodle and now this is handled in a different way.
The API is basically just used for the app to communicate with the server, rather than the API being used for extracting data etc.
We’ve not yet had chance to update the API docs on the main docs, which is why it’s been removed from there (I thought best not to have the docs at all if they were not correct and up to date).
However you can view the endpoints code at:
https://github.com/DigitalCampus/django-oppia/tree/master/api/resources - for the general endpoints the app uses
https://github.com/DigitalCampus/django-oppia/blob/master/quiz/api/resources.py - for the quiz attempt tracking
Hope that’s useful?