Some questions have asked this already: Is Google Drive RealTime API for Android?, and Does the Google Drive realtime API support Android?
However, it was described by one commenter two years ago as a "high priority" for Google, and I know that the Drive API capabilities for Android have greatly increased, however, there seems to be no Google documentation I can find on the topic.
So what are the options for using the Realtime API, or collaboratively interacting on realtime files in Android?