Control UI with USB gamepad
I use an Xbox 360 USB gamepad and it maps the Xbox and Back buttons to Android Home and Back. I wish it wouldn't, it's very annoying to have Chrome back-navigate when you're trying to play a game! That said, it sounds like it would work perfectly for your case.

Gamepad->keycode mappings on Android are configured in .kl files. It looks like Android doesn't have a mapping for DragonRise 0079:0006 so maybe you just need to create one. Here's the file for the Xbox 360 USB:

https://android.googlesource.com/platform/frameworks/base/+/master/data/keyboards/Vendor_045e_Product_028e.kl