I tried probably 10 keyboards in a very short period when I had wrist pains. The Glove80 completely solved it for me and I never have pains anymore. I would rank from highest importance to lowest:

- Regularly exercise, including proper exercise for your hands/arms.

- Height-adjustable desk + good chair, so that you can micro-tune the height to have straight wrists, etc. It should probably be electrically adjustable, my experience is that most people do not properly set the height if it's more effort to change height.

- An ergonomic keyboard. For me, it has to be column-staggered, split, with thumb keys and a key well. I have reviewed some flat keyboards after switching to key well boards, but discomfort comes back after a few days to weeks.

- A keyboard layout. So, this is the part where I disagree with you. Switching to non-QWERTY is maybe the last 5% of optimization. There is one catch though: an alt layout becomes more important when switching to split column stagger, since you cannot alt-finger as easily and the very frequent letters T/N are in a bad position on columnar boards.