Isn't the point of CarPlay and Android Auto to make this possible, without needing to actually replace hardware? The idea is to make it so the hardware in your car is just a dumb terminal that doesn't ever need to be upgraded. Your infotainment system gets upgraded every time you get a new phone or iOS/Android upgrade.
Sort of, but they don't let you control things like... climate control, etc.. There's no real reason those APIs can't/don't exist as long as they have proper safety mechanisms in place.
There have long been CarPlay and Siri intents for things like climate control but no automaker has wanted to give up more control inside their dashboard.
