Why can't you use m3 MacBook Air keyboard with two external displays?
Why do you need to use an external keyboard with the MacBook Air in clamshell mode?
Why can't you just turn off the internal display and use the MacBook Air keyboard?
Maybe you could trick the lid sensor with a magnet so the lid stays open and the keyboard is exposed, but the display turns off? Hopefully it doesn't also turn off the keyboard when the lid detects closure.
You couldn’t reach the keys in clamshell mode.
But as for why you can’t turn off the display, I suspect you can somehow.
because Apple designed it this way so that you'd spend more $ on the Pro model.