Later Android versions do support this… It’s just called Multiple users (or a work profile but I think you need Google Workspace to set that up).

You can set up a new user as a sandbox for these types of apps and shut them down when not in use.

Yeah. I definitely prefer Android Auto/CarPlay as a car agnostic interface for media and navigation over any built-in thing.

I’ve worked in this space in the past, and unless car manufacturers have significantly improved their UX chops this will go terribly. Further, this just seems like an opportunity for GM to further DLC’ify the car. Generally Android Auto and Car Play would be standard on even the lowest models, but now you might have to pay a monthly subscription to access this