there's two things that make my hands cringe: drag-clicking (e.g drag file to trashcan) and mouse-wheel click (close chrome tab).
I built a trackball into my split keyboard and now I move it with my right hand and perform al clicks on my left hand side of the keyboard.
I use a touchpad when possible knowing that, but I've never double checked myself. Anecdotally, I've only developed RSI in my mouse hand from gaming (same story for my friends who game as well).
NHS seems to back this as well: https://www.nhs.uk/live-well/healthy-body/tips-to-prevent-rs...