Using any standard usb switch or KVM breaks the air-gap, as malware can (and has been known to) spread via kvm and USB switches.

Here are the solutions I am exploring:

- Use a mouse and keyboard via bluetooth, using the switch inside the device to switch computer. For example the logitech MX mouse can switch from one computer to the other. However, does anyone know if it's a hard switch from one computer to the other, or if the mouse stays connected to both?

- Create link (via usb or serial) from one computer to the other, to use the keyboard and mouse from one on another. That breaks the airgap, but maybe there's a way to make the link simple and secure enough. I had a lot of great advice from another post here, but I think I need to explore other options as well.

- Use a mechanical usb switch that physically disconnect the a path when switching to the other. I search a while on the internet, and couldn't find a device like that. They all keep connected to both.

Does anyone have any advice?