@qnx_guy I have no specific experience with the F(x)etc, but I've had a surprisingly good experience with the Microsoft Miracast V2. It seems to only be available used though, and is expensive.
Mine has latency that seems to be less than 0.5s, which I find quite useable. And yes, the device becomes a touch pad mouse when connected, though you can also connect a BT keyboard and mouse.
But it does seem like most people have a less successful experience than me.