The eternal pattern of the industry is that a automanufacturer has negative interest in remaining interested in an infotainment system in a car they sold several years ago and retrofit makers provide less specifically integrated systems that win overall because developments in everything else amounts to more than the integration.

You can use almost any app, not just apps that Tesla have deemed worthy (or removed due to childish feuds, like Disney+). Podcast apps, music streaming apps, etc...

Well I have some audiobooks downloaded to my phone. The progress is saved on my phone, and because they're downloaded I don't need cell service to listen to them. I just did a 3000 km road trip with intermittent cell service, using an app on my phone via Android Auto to play my audiobook files, and was able to easily transition to hotel rooms with speakers, and different vehicles, and continue the books where they'd been paused.

How would that even work in a Tesla?

When I plug in my iPhone, the Maps is integrated with my Calendar. For example if my Calendar entries have a Location, I can simply tap on it to navigate there.

Just one example.

It's not, it's just superior to what Nissan had before integrating apple carplay/android auto. It's so much nicer being able to interact with both my actual car and my phone through the screen, instead of just playing with my phone on a larger screen.