Given how many cars have Carplay or Android Auto, but also have their own e.g. Toyota app that you need to/ought to install, it feels as though this isn't that far off from how things basically are.

Personally, I'd be happy with some kind of situation where:

1. You have a small in-dash touchscreen, as most small sedans have these days, as the basic level of "backup camera and radio view" 2. Everything the car does has a physical button so you don't NEED to use the touchscreen 3. The car has a USB-C port that can power a tablet and which provides a standardized interface that e.g. iOS and Android can interface with, so that users don't have to worry about their new OS doesn't support the not-updated app, or the app doesn't support their not-updated device 4. Sell an optional tablet mount that attaches to the dash the way a built-in one would be 5. Sell an optional 'tablet' that does nothing but interface with the USB-C port and provide what it needs, in case someone wants a larger screen without having to buy an iPad Pro

Then again I don't drive, so I'd be happy with none of this also.

Honestly, I'd be okay with this, and then you can upgrade / replace said tablet if you wanted to. In an Alternate Universe, your iPad drives your car, your iPad Pro drives your car through hell and back, or whatever.