On the full-sized X32/M32 you can press "Remote" to enable MIDI control of some other device. Can control be extended to the Mixing Station app where these faders and buttons can be changed remotely from a tablet when they are in "Remote" mode?
In theory this should be possible if you connect the X32 via USB to an android device and assign the buttons there. But the X32 midi interface is not recognized properly by the OS. Might have to write a custom driver for it.