Can you use a touch screen or mouse? I went ~13 years without using a keyboard, and typed with mice (some customised), trackballs, and touch screens, mostly using predictive typing software I wrote. In that time I did a lot of programming, including a whole applied maths PhD.
One of the best mouse setups I came up with a variety of versions of was moving the cursor with one hand, and clicking with the other. Holding the mouse still to click the button accurately is a surprisingly problematic movement. I made a button-less mouse with just a flat top to rest the side of my hand on, with a bit sticking up to grip. Standalone USB numeric keypads can be remapped to mouse clicks and common keys.
Touch screens can also be very good, if set up right, as all the movement can come from the big muscles and joints of your upper arm and shoulder, and your fingers and wrist don't need to do much. The screen needs to be positioned well, not out in front of you, but down close and angled in a comfortable position to hold your arm for long periods.