So I found out that the PS4 controller is a true Bluetooth gamepad. You can force to pair with another device by holding "SHARE" + "PS" until the lightbar flashes white, then searching for BT devices on your phone/tablet. Frustratingly, it -almost- works with VO, but the mapping is a bit screwy:

L1 and R1 (shoulders) are not recognised at all.
L2 and R2 (triggers) each map to a different axis (Rx and Ry, I think?) with strange calibration. With a bit of config you can map them to some control functions though; mapping to "turn" works, but frustratingly, "roll" doesn't work well. You -can- roll a little bit by hammering the trigger.
L2 -also- maps to "fire". So you can't use it to turn without firing.
L3 (left analog stick click) maps to "options" somehow.
R3 (right analog stick click) maps to "zoom".

Other axes, d-pad and buttons seem to work fine,

Happy to test more and provide feedback if it helps to support this device.

Its a well known issue with even PS3 controllers, and its not just android either. You can use a tool called six axis controller (requires root, and even then not supported on all devices) to make the controller work as it should. Its a paid product but there is a demo available that will show if it works or not.

Even on Windows/Linux/OSX you need some 3rd party software, like motionjoy to make these controllers function 100%.