If you want to experiment with Android on Pi, there is an experimental download here:
http://konstakang.com/devices/rpi3/LineageOS15.1/
Seems pretty rough right now, so don't go thinking you will get full gaming or even application experience, it is more a proof of concept.
The main use I would suggest is for people to play around, experiment, or for people developing Android apps to test the platform. Pretty sure it will crash often and would be more of a proof of concept than a daily driver!
(You CAN enable root, unlike some of the discussion in the groups)