Using the new playdate.serialMessageReceived(message) API I've created my own solution for mouse support/control.
With a few caveats:
- mouse forwarding script is macOS-only right now
- works only with the device connected over USB
https://devforum.play.date/t/matts-prototypes/826/201
Would be much better if the Simulator had this built in, perhaps as an option, and that it also forwarded mouse events to a connected device if "Control Device with Simulator" was checked.