The integratedness of Apple's offerings depend on the control they have on both software and hardware. I think it's the integratedness that sells Apple's product.
Agreed. But the point I argues was that Apple does not care because they sell hardware either way. I think they care a lot their hardware is used to runt their software, as this is a big reason to sell more hardware.
NT is very much legacy code in maintenance mode, switching to something that's more modern that's also the base for Android makes a lot of sense.
Nowadays, especially on iOS, it seems like the software is the focus. I'd argue that's a mistake that will sooner rather than later bite Apple in the ass. Hopefully the switch to M1 is a sign that Apple realizes this and wants to move back toward making top-notch hardware instead of coasting on App Store rent-seeking and planned obsolescence.
However, considering Apple's behavior around iPhones and iPads, I don't expect those hopes to come to much fruition.