(For the record, my wife swears by hers - helps with the RSI. I use a Magic Mouse. I have a box full of input devices, including several from Logitech, that I've tried and they didn't work for me.)
I think mice are kind of inherently bad for RSI type stuff. I've used *so* many kinds over like 30+ years, and haven't found one that is truly great in this regard. Some are better than others, but they still give me issues. That's another issue with my MX Master. While it's really full featured and there is a lot to love, it isn't as comfortable as it looks.
I have found, as it seems your wife has, that trackballs can help. I'm not sure about trackpads, but I don't find using my laptop to be comfortable... but maybe that's due to it's position on the laptop and size, etc. I need to give that another shot. Otherwise, I'm probably headed back to a trackball too.
One of my friends actually deigned this mouse to try and help in terms of ergonomics, but I've never really liked it. I know it's used by a lot of companies trying to provide ergonomics solutions to employees. It probably works in that regard, but I just didn't like using it.