Computers still only have three mainstream input devices, keyboard, mouse and gamepad after 60-80 years I'd try and bring the addition inputs a smart phone has to computers, like touch. I know there are programable keyboards and many other things. But no one has cracked it yet. It's a cool project as is. Just an idea if you were thinking of iterating forward.
There are lots of computers with touch capabilities out there. From the gesture support on Apple’s trackpads to touch screens like the Surface (and plenty of other laptops with touch screens). There are also stylus inputs and things like Wacom tablets that have been around for many years now.
But really, the problem being solved by OP was not enough outputs, rather than not enough inputs.