This app was mentioned in 2 comments, with an average of 2.50 upvotes
The Android OS itself supports gamepad input and navigation. The fuck more do you want? App developers take advantage of the touch screen interface since it's the only constant on Android devices.
Have you ever played Anomaly Korea or Anomaly 2? How about Riptide GP2?
Those are just the ones I can recall immediately off the top of my head. There's a massive list on the Amazon store of all the games that support controller input (of course, that's just the Amazon store. There are tons more on Humble and the Play store, but neither allow for filtering searches by controller input).