It is my understanding that the Apple Carplay is simply a repeater for your iphone. I really don't know much about this but last week at a club breakfast one of the guys was talking about his. He said that as long as your phone was within range, the carplay was a duplicate screen and you had all the functions of your phone. As I understood him, the phone is doing the heavy lifting - the Carplay is an interactive screen that communicates w/ the phone. I have no idea about the camera - presumably one would not want a picture of the inside of your pocket.
Really quickly on this, I have a CarPlay unit on my bike after having fallen absolutely in love with it in a rental car back in 2020 and deciding my next car (the one I own now) would have CarPlay.
It doesn't mirror your phone. It brings some functionality of your phone forward to an interface that's very similar, and locks down some use cases while in motion.
There's no web browsing on it. You can text and read texts (as well as some other messaging apps) while stopped, but while moving it will only allow you to listen to them read to you and convert your speech to text as a reply.
Music and podcast playback work wonderfully, regardless of the app, but again, no keyboard control while in motion.
No video playback.
Most importantly is navigation. Regardless of what nav app you use on your phone (Google, Waze, Apple Maps, Bing) it's available on your CarPlay unit, bouncing off your phone. Can't use a keyboard while in motion, but you can voice search for destinations and both hear and see the directions.
You can't really "add" apps to CarPlay. If an app on your phone is compatible, it will work with CarPlay and show up there automatically.
What I love about it is that my phone stays in my pocket or charging in the top box, away from the elements, and I can still use the basic functionality. I can take or make a call without any issue at all, which is nice. I can see notifications come in, even if I can't do anything with them, which might be enough to tell me I should pull off. I'm not being distracted by them.