This is kind of a grab-bag comment based on the discussion so far.
I think it’s more likely that macOS turns into iPadOS than macOS ends up on an iPad. (I don’t think macOS turning into iPadOS is likely at all, even though the OSes are borrowing more and more from each other.)
I like macOS, but I think it would be horrible as a touch interface. Moreover, modifying it to work for touch would be a terrible idea. Why surrender the precision and elegance of macOS so that it can accommodate our fingers, especially when iPadOS already exists.
The problems that @cornchip identified are real technical challenges the solutions to which do not seem like they’d improve either the iPad or the Mac.
Based on what I’ve read here over the years, the people who want macOS on iPad seem to fall into three categories: (i) some just dislike the iPad interface and vastly prefer macOS; (ii) some struggle with certain hardware limitations and software restrictions, e.g.,: no terminal; absence of multiple audio channels; less robust background operations for apps; and file system quirks; and (iii) some seem to be irritated that certain apps they want to use don’t work as well on iPad. My sense is that group iii is the largest and that migrating macOS to iPad or offering macOS on iPad is a less desirable fix. The better fix is convincing third-party app developers to treat their iPadOS apps as first-class citizens. Make the apps function seamlessly on iPad and I bet Apple eliminates a great number of the people clamoring for macOS on iPad.
I’m not sure exactly where you fall in my taxonomy (or somewhere else), @Shruggie. Maybe you could share some more about what could be improved by having macOS on iPad? Because maybe an evolving iPadOS would be able to serve your needs in someway other than a wholesale migration of macOS to the iPad.
+1
+1
At my firm, we are PC based and use thin clients and login with Citrix Workspace. So, I spent a lot of time navigating Windows with my fingers. It was not fun. Using Windows through Citrix on my iPad with a trackpad and keyboard is a breeze. In fact, using it on an external display from my iPad is almost no different from using it on the desktop. The only difference I run into has to do with transferring files between the iPad and the Citrix Windows instance.
I don’t think my windows desktop is configured for touch (i.e., maybe it does not have HID-compliant touch screen active), so this is not a perfect comparison with using macOS on an iPad or using macOS as a touch interface. But it’s very clear to me that there is a huge distinction between using a touch-centric interface and a keyboard-and-pointer interface that just happens to permit touch control. It is an unpleasant experience to say the least. Also for people just using a software keyboard on their iPad, it would be terrible using macOS when 50% of the screen disappears. Surely, these are technical problems that smart, creative engineers could solve. Not sure that would be a valuable exercise, though.