[Aeglos]

In response to using a TI LaunchPad-
It would be much simpler, at least in my opinion, to use a Raspberry Pi Zero, as it is so inexpensive and abundant. It can pretty easily pretend to be a joystick with as many buttons as you want, and will have a LOT more support from outside sources and forums due to its much larger user base than the TI LaunchPads.
Interesting and somewhat related side note- if I remember right from my tinkering with the Pi, the Driver Station pitches a fit if you have a joystick with more than 32 buttons/ axes/ pov's combined, so keep that in mind when constructing your interface regardless of controller. You might have to double up on microcontrollers if you want anything incredibly complex.