if you're going for a big monitor, you might want to consider getting a TV instead, better $ / screen real estate
4k TVs start at 40 or 41" and one of those can easily replace a 2 or 3 smaller monitors setup, simply because you can arrange your apps in windows across all 4 corners and because of size of display + the higher resolution, they'd still be big enough to see what you're doing
they go for 200$+ for the Chinese brands and 300$+ for the big name brands and you need to have a pc or a laptop with an HDMI 2.0 port, if you tell me what you got I can tell you if it's going to work. this feature is not too common in laptops but if you have a desktop, most likely it's there or you can adapt from a Display Port to the HDMI on the TV
as for mice against carpal tunnel, I'll put a list of designs you want to look for
vertical
https://www.amazon.com/Wireless-Vert...397700&sr=8-20
slight variation in shape and the way you grip these, some are more "vertical" than others, depending on where in your wrist it hurts, one type will work better for you than others. I personally like this one because it's a bit easier to use than the ones that are close to a 90 degree angle. takes about a week to get used to one and then it's smooth sailing
trackball
https://www.amazon.com/Kensington-Ex...s%2C312&sr=8-3
there are cheaper trackballs, but I didn't much like any of the other ones I tried. most have smaller balls, which you can't wrap your hand around, some are designed for your thumb to operate the ball, which is fine for your wrist but then your thumb starts hurting. this particular model, with the included wrist rest is super comfy once you get used to using it, prob in a week or 2.
if you do a lot of writing and want an ergo keyboard, I can help you with more details, but if you don't type a lot , you don't need one, they're not a big deal