Just whats been around tbh. Some old speakers with a cheap bluetooth amplifier board f.e. One of my flatmates added his PC speakers with subwoofer and we got a sourround system running along side it. Didn’t spend anything just connected whats been already around.
Theoretically of course :D The Software side shouldn’t be that hard either so if you get the motor somehow connected you could get fancy rumble instead of the haptic feedback which you can currently enable.