"our" is not the royal we here, this person refers to themselves with a plural sounding pronoun for identity reasons. They are not making a statement about ergonomics generally even though of course I can see how that can be confusing.

There's nothing really hard on healthy people when we use touchscreens, but this person clarifies they are disabled so this sounds like an edge case for them because if you're disabled in some ways, a nice fat keyboard is just going to be a lot more gentle on your hands and fingers than the tiny thumb keyboards of mobile devices.