Apple's UI for establishing the connection — the little squish and pop thing that happens on the first attempt — is really brilliant. I think it's likely to cause some consternation when it doesn't work perfectly (as is their bias), but if it works well it'll be a great boon for those of us who like to use multiple computers at once.
I wonder how they detect device orientation. That part is utterly magical to me.
Barrier (a FOSS fork of Synergy) and Synergy are the only solutions that work across all 3 major platforms (macOS, Windows and Linux/X11)
Unfortunately they're buggy as hell, feature incomplete (no drag and drop), and ipadOS and anything Wayland based is unsupported. You also can't control macOS input unless the user manually grants permission (after installation) and on Windows there are still issues with privileged screens by default.
Imho the best commercial cross-platform (Windows and macOS only) tool for the job is Sharemouse, which has a bunch of value add features like multi-machine lock and unlock.
https://www.microsoft.com/en-us/download/details.aspx?id=354...
http://graphics.stanford.edu/papers/pointright/