This seems similar to Barrier in Zorin OS. Not across tablets and such, but across Zorin OS devices. I remember using this to share keyboard/mouse across my desktop and laptop, but I rarely end up actually using it.
It seems like one of those things that is interesting in concept, but I can't say I'm seeing the need/use case for it outside of that...
For the record, the upstream version of Zorin Connect (KDE Connect) is available on all Linux distros, and also supports mouse control on Android devices.
It seems like one of those things that is interesting in concept, but I can't say I'm seeing the need/use case for it outside of that...