I have deformities in my wrist and I have small palms (dwarfism) I’ve tried various kinds of mice; none of them were comfortable and settled on using a Wacom tablet as a trackpad.

Recently I started using Logitech Ergo M575 trackball mice and it has been total game changer, I can even play FPS games quite well with it. I highly recommend trackball for those with accessibility issues like me and certainly welcome more open hardware competitors in the space like Ploopy as customisation is crucial for accessibility.