Arbitrary is doing a lot of work. With MacOS you can use an iPad as a touchscreen external monitor. Try it and you’ll learn that it’s not a touchscreen OS. It’s not as simple as “not letting you”.
Maybe it doesn't have a touchscreen interface, but i take issue with it being a touchscreen OS. I suspect most people who would want to run MacOS on an ipad would attach the appropriate user interface devices.
or...plug into usb and use the ipad battery. the ipad already has a battery. Just don't limit what software you could load, that's all that's being asked here.
They could have a lean version of the macOS desktop on every iPhone where it would switch to the macOS desktop once you plug it into a display. Include iWork on both sides with shared storage and you could switch between the phone interface and macOS.
I mean Samsung DeX has done something similar, but Apple could make a much more powerful version, since they have a real fully-developed desktop and they have apps for both platforms that use a single code base.
They will, of course, never do this, because it would result in losing Mac sales. Though I think less than one would initially think, because a laptop is much handier on the go than carrying a separate display, keyboard, and mouse and the lapdocks or whatever they are called have much worse displays and keyboards.
