Hi, can I help

[Em-Lopez]

I've never done android development, successfully that is, and I'd like to contribute a couple things to your project. specifically:

Since the user will essentially be blind while using the app, I'd like to make the controller usable with only the thumb while blindfolded. So like maybe Home would correspond to double tap swipe up and System would be double tap swipe down, and grip and trigger would be volume up and volume down, being configurable, since everyone's android phone is different.

[peter10110]

I've already abandoned the project, but feel free to modify it, as you like.
A couple of notes to your idea:
I totally agree, that its almost impossible to use a touch screen while being blindfolded. That's why I mapped for eg. the trigger to one of the volume buttons. But even that button doesn't have a consistent place on different phones. The major problem with the system buttons is, that I don't think, that Android would let you remap those, unless some rooted magic. Also, newer phones tend to use gestures or at least software buttons, so using those wouldn't make a difference.
I think the whole concept of using a phone as a controller is far from practical. I built this for testing my SteamVR driver, before I've built a dedicated custom controller for it.