I went down this path and tried various vertical mice, and settled on the MX V for a few months in the pursuit of reducing wrist pain. After about 4-5 months or so, I started getting strong wrist pain again, and switch backed to a standard mouse. At that point I started looking elsewhere, specifically on strengthening my wrists and joints. I've been doing this about 5 times a week for probably 5 months now, and most of my mouse hand wrist pain has subsided: https://www.youtube.com/watch?v=iVum3vWlh4Q

Thanks for the video. I’ll definitely try it out. In my original post, I should’ve emphasized that I’ve also been focusing on strengthening/mobilizing my wrists. It’s only been a month or two of concentrated effort, but I think they’re improving a bit.