PlatformInfo isn't really a solution. I don't need to detect the platform. I need to know when "On Touch" is triggered - whether it was really a touch event or a mouse click.
That official example is using Touch with mouse input disabled.
Just use is overlapping with a dummy object.
Not sure I understand how it would help. Say, when playing on Steam Deck, you can use the touchpad (mouse) or touch the screen. Or even connect an external mouse.