There’s an app called Synergy that lets you seamlessly move mouse and keyboard input between devices, if you ever feel the need to run the Mac and the Windows machines side by side rather than using a KVM switch.
Not sure, but that's definitely a particular thing Synergy does alright. I do find it's a bit meh still between OS' but only in some cases where you might have a full-screen game open on one computer and other non-full-screen content on another.
I personally just use a kvm to switch between computers on my desk with monitors that are dedicated to them because of issues with synergy. But also synergy doesn't work with vpns.
Synergy worked great without perceptible lag for normal desktop stuff in the late 90s (including across all the steam powered pcs in the school computer room).