I think you're missing my point. If - and that's a big if - macOS ran on an iPad using a mouse/trackpad + keyboard in a more productive way, you'd also be sitting at a desk with the iPad powered either by an external display (the iPad behaving like a Mac mini for instance) or directly from the charger.
I mean, what else to expect? Using macOS on an iPad with a mouse/trackpad + keyboard while on the couch or in the bed? Of course not. So that's for the battery issue.
Also, over the years there were numerous leaks here about Apple running macOS on an iPad in their labs. There's no question a Mx iPad can run macOS.
It’s not just about the battery though, and like I said it’s not about it being physically possible.
There are still absolutely thermal limits with the iPad that just don’t exist with even the MacBook Air, and even being directly plugged into the wall isn’t going to help, and being plugged into an external monitor might even make things worse seeing is that uses more processing power to push the extra pixels.
Once again, yes, of course Apple has internally tested macOS on the iPad. And they probably found, that as soon as you start using it intensively for anything, it becomes a trash experience.
Sure, if you leave it sitting on the desktop with absolutely nothing opened, it might technically run.
But the second you start to do anything, macOS’s significantly more power hungry RAM management will bring the iPad and it’s tiny thermal envelope, it’s tiny battery and it’s significantly lower power draw to its knees.
Again, we are talking about a product with about half the battery, half the thermal envelope and very small power draw.
Even just a couple Safari tabs easily uses over 9 GB of RAM on my MacBook Pro with 16, I can tell you with absolute certainty that that is not the case on the iPad Pro.
Fundamentally different operating systems, made for different form factors. Again, this goes beyond touch and keyboard and mouse.
I get it, iPadOS is far from perfect, there is tons of room for improvement and areas where using a Mac is just better. That’s undeniable. I have experienced that, as a user of both an iPad and a Mac, I know this to be the case. I am absolutely not denying that iPad software dramatically needs improvement.
But I also understand why they don’t just force it to run an operating system that is clearly not meant for it, that will actively cause it to function worse, throttle easier, and will bring the battery to barely usable levels.
We can argue that Apple should make a touchscreen Mac convertible all day, but that’s the thing. For a tablet to run macOS, they would first need to do some dramatic hardware changes. Just because the iPad and a MacBook happened to have the same SOC means very little.
The original HomePod and the iPhone 6 used the same chip, it’s simply does not mean anything when the form factor will not comfortably support it.
I think it’s very likely that if you boot an iPad into macOS and then try to run Final Cut Pro or logic pro, eventually, the thing just stops working, because it can’t handle that type of load. Back to my analogy earlier, it’s like trying to use an Apple Watch to run iOS. Sure you might be able to flip through the home screen just fine, but open a mobile game and the thing will likely die or overheat before the loading screen is finished.