If you were writing the consuming app, you could get analog support with an ADC into a decoder into individual or combinations of keys. I say you'd have to be writing the app because I don't know many existing apps that support that sort of key binding (though I do seem to recall MS Flight Simulator doing it, at least for throttle).
I do refactor parts (I've done the keyboard thing mentioned above) but now since I'm older I realize I don't have the time to dork around with a dodgy keyboard (ummm is that the reason I tossed it into the junk bin?) and want things to work after I fix my design errors, not after I fix a broken part.
I'm more a pragmatic Maker. Can I run to Home Despot and buy wood, fasters, plan, cut, assemble and install shelves? Yes. Can I go to Ikea, buy something close and make it fit that then looks really nice? Yes. With 400 linear feet of shelving in the robot lab, sometimes Ikea wins.
Likewise, some nifty Adafruit board is the quicker way to win.
Using a digital joystick would then be the way to go. I like his choice of that input device.
But, like Quequau, I've never been able to get into Kerbal. I guess I could go whip a panel up, but at the end of the day not sure that it would be enough to catch my interest.