MacOS and iPadOS technically are running on the same kernel and have different kernel extensions. Theoretically, it should be entirely possible to instantly switch between iPadOS and MacOS on the same device running the M1 chip.
I suspect that's what Apple is heading toward, but... let's be realistic: if I can run MacOS with a complete touch interface on my iPad, and have perfect external monitor support, there would be absolutely no reason for me to own any MacBook at all.
It can be done easily. It takes very little work for Apple to add touch support to OSX.
But you know they will never do it, because now Apple can sell you a MBP + iPad Pro.
Something has to pay for these Apple commercials of Mission Impossible.