The big buttons could be filled with a big bright led. That's quite nice, I have to find a way to drive it from the Raspberry pi GPIO.

I have around Mosfet IRF530, but the need more than the Rpi 3.3v level to drive a reasonable current. I added quick and dirty transistor BC547.

To connect the button to the raspberry pi, I configured the GPIO with a pull-up, and the button shorts to 0V.