Deskflow by Synergy's Symless Team. Wayland Supported Now (github.com)

Adds support for Wayland with its latest release.

It also supports the downstream forks of lan-mouse and input-leap.

Thought it sounded familiar. Relied on Synergy for years, until the version 2 transition. Was a total mess, and I just stopped using it.

Adapted my workflow and haven't looked back.

See they've made a version 3, perhaps time to try again.