No. The macropad would be connected to one PC which would be the controller, so you press that regardless which output is selected, maybe this wasn't clear. But this is only needed to trigger - theorietically it could be triggered by a third device (eg RasPi connected to the display(s) via HDMI).

Maybe to add, this is also better than a KVM because it supports any number of display outputs which you can connect between the two devices. It's more practical to use a USB-C dock though.