IIRC by design applications can't get the absolute mouse pointer position in wayland, so something like Synergy probably is not easy to do in Wayland without 'hacks'.
The closest I’ve found in terms of description is https://github.com/feschber/lan-mouse, but the lack of encryption on the connection has discouraged me from using it.
I’m also a paid Synergy user, and it’s frankly comedic how long Wayland support has been on their road map. I’m not convinced it’s ever coming, which means I’m probably only 1-2 distro updates from being forced to use something else