Preface: I cannot take credit for the project shown in the attached video and photo; 100% of the credit belongs to Hrvoje Čavrak who created the DeskHop project (https://github.com/hrvach/deskhop)
Do you use two computers at your desk, but share a single keyboard/pointing device between them? Do you use some sort of switch to do that, or worse, move cables between them, or even worse, do you use some sort of software solution like Synergy, Barrier, or Universal Control (macOS only)? Do you wish you had a better option? Guess what, you do!
DeskHop is a small device composed of two Raspberry Pi Pico boards plus some additional components and some amazing open source software. You plug your keyboard and pointing devices into its inputs, and plug its outputs into your two computers, and... that's it! It just works, as you move the pointing device and the pointer moves to the edge of one screen/computer, it pops over to the edge of the other screen/computer and the keyboard moves with it. It's truly magical.
I forked the project and made some small changes to the PCB so that I could get a 10-unit production run made by a Chinese PCB company, and the boards arrived last week; the photo is one of those boards. Nearly all of those 10 boards are spoken for already, but I could do this again if people really wanted them (total cost including USPS shipping in the USA is about US$35).
@johns It's completely external to the computer, the software on the computer is mostly irrelevant.
With that said, both of the machines I'm using are running Wayland.