Mice & Pointing Devices
It's kind of crazy how little attention mice and pointing devices get considering their centrality to the computer-using experience.
From just scratching the surface of trying to improve this aspect of my work setup, some tools I've settled on are:
Vertical Mice
I'm a huge fan of ergonomic and vertical mice (next on my list of things to ergonomise is my chair!).
I like them so much that they've been added to the list of unwelcome presents you might get from me whether you want it or not just because I know they're great. So far, however, I boast a 100% success rate in inducting recipients into vertical mice.
I own both the Logitech Lift and the MX Vertical but the MX Vertical is my preference (check how you tend to naturally grip the mouse; it's an important determinant in finding the best product).
On Fedora, Solaar picks up the device without effort and has options for remapping buttons. There are a few other mice config tools too if you poke around the repos.
Trackballs
I have a soft spot for weird people, weird things, and obscure tech that never quite made it big even though it probably should have.
I would include standalone trackballs in this category.
Although reportedly beloved by architects my wife, who is an architect, attests that she has never seen anyone actually use one of them. This endears them to me