I agree. I blew out my left arm for a year from too much typing, so I switched to kinesis style keyboards so I could put modifier keys under my thumbs. I dunno if your suggestion was meant to be serious, but it's still great.
What would be a cool use case for thumb controls here? Is this something you could do with those gamer keypads?
I switched to a Kinesis Advantage keyboard and now I have control, alt, hyper, super, backspace, and shift under my left thumb. My right thumb has control, alt, hyper, super, enter, and space.
I don't know anything about gamer keypads, is there one you suggest I investigate?