I ended up restarting both devices to get it to work on my M1 Air and iPad Pro, after turning the various settings on and off a few times. It's unclear that you even have it working, but when it does you can try to move your cursor off the screen (not sure how it decides which side of the screen), and it will pop over to the iPad.
The "beta" label seems to be accurate though. It's laggy, keyboard shortcuts don't seem to work (cmd+h for Home Screen, for example), and at the moment the iPad and Mac have opposite ideas of whether caps lock is on or not. I have to hit caps lock after switching between the two.
I've used Synergy to have various machines work together like this, and when it's working well this will be very useful!