Comment by anonymousiam

You could do this with a couple of TI MSP-EXP430F5529LP boards (<$16 each from Digikey). They include demo code with HID features. I've used this platform extensively, but I never used the USB features for anything other than a JTAG interface for development. I once recommended it to a friend with no embedded development experience, and he had his own custom "mouse jiggler" up and working in one day.

https://www.digikey.com/en/products/detail/texas-instruments...

Alternatively, the newer ESP32-S3 boards (<$6 each) have dual USB-C interfaces, so you could do it with only one (smaller) card instead of two. Development might take longer though.

https://www.amazon.com/dp/B0CN4789XC

If you want to allow a network connection between the two computers, you could load soft-KVM software on each, and go from there.

https://goinglinux.com/open-source-cross-platform-kvm-softwa...