How to allow mouse pointer to move to smaller display?
Don't think possible for the reasons Tetsujin noted above. In past my workaround for different sized monitors was to position them corner to corner - e.g. top left or top right. It was easier to remember (for me) that the mouse would only slide to the other screen if I put the pointer in the corner of the current screen. Also meant windows I slid to the edge of current monitor would not accidentally slide partway onto the other screen.