The Datahand / Svalboard branch is even more niche than a standard mech board. They are really designed for people who are facing injury, injured, or have been injured.
I'd encourage you to look at the Svalboard, I think it solves many of the issues you are running into. In the end, moving a large mouse is not good for someone with shoulder issues, the "Svalmouse" has been tried and solidly rejected. (Using a Svalboard hand as a mouse.)
If you want to discuss things, I'm sure you can find me on the Svalboard discord. :)
I'm not sure you understood me: it looks like the ergo mouse (form factor, ergonomics) but is most definitely not a mouse. As I said though, it seems more difficult to get a keyboard to fit a variety of hands in this form-factor.
I'm referring to "svalmouse," that's not what I'm thinking at all. The only mouse thing about my design was the form-factor, the shape of the shell, the fact that it's vertical.
I'd encourage you to look at the Svalboard, I think it solves many of the issues you are running into. In the end, moving a large mouse is not good for someone with shoulder issues, the "Svalmouse" has been tried and solidly rejected. (Using a Svalboard hand as a mouse.)
If you want to discuss things, I'm sure you can find me on the Svalboard discord. :)