Mobile Input/ VR

I am wondering, how does one connect a bluetooth gaming controller for android to the mobile game that they are running? What action mappings are involved with bluetooth. I guess the real question is, How can I create a game that uses those inputs (left joystick, right joystick, box, circle, triangle) from a bluetooth controller to interact with my game and character component? Also, if you are knowledgeable, is it possible to tell the game to work in gear vr mode, yet use a mobile bluetooth controller to move “you/the character”, around that vr game. Like maybe one joystick moves forward/backward/left/right while the other is absent and you use your head to “look”. I work in blueprints, so I don’t know any c++. Thanks.

more info.
I’m trying too hook these two up with my android phone…