I think what would make this amazing emulator perfect, would be a customisable built-in gamepad, similar to the ones in Mame4Droid or Fba4Droid, where you can adjust a lot of things like animation, vibration, size, position and range 
I know there are a few good overlays out there, but none are quite as good as a fully customisable one could be.
We don’t want to put something like that inside of RetroArch but we have discussed making an external program that outputs an overlay. This is an area where a normal android programmer could help out, since it wouldn’t need to be low-level-C-via-NDK like RetroArch itself is.
YES!, i’m glad you’re looking into it.
thanks for answering 