Sorry, I know you wanted to communicate a lot with that paragraph but I gotta ask - what keyboard do you use? I want to avoid carpal tunnel myself but haven’t been able to find any recommendations online.
I use the ErgoDox EZ (https://ergodox-ez.com/) with those sculpted caps that come without letters printed on them. I love this keyboard: it's one of my most prized possessions. I only wish they'd made one where the sculpted caps do have letters printed on them. This would make it possible for other persons in my household to use my keyboard.
You should aim for orthogonal and spitted keyboards. Big changes, you possibly need to relearn to type, but potentially life changing. One model among others which is safe for recommendation is Ergodox EZ. Warning: not cheap, none are.