I think you may have my thoughts about CarPlay wrong. I do like CarPlay, I also said to myself, I would never buy another vehicle without CarPlay. But then I bought a Tesla, and loved it so much I sold 2 vehicles and got a 2nd Tesla.
I agree in your use case, having CarPlay to run control your Overcast usage would make your user experience better, I do not disagree here. Most of my listening is like yours, radio shows on SiriusXM where I listen to several channels, or shows in podcast form (streamable after live show).
I spend 3 hours in my car a day, 1 hour in, and 2 hours home. I go between my SiriusXM shows, kids' channels since my son to be 2-year-old sone rides with me (his daycare is at my job) and music saved on my phone. So, I spend a lot of time listening to the radio in my TMY.
What I disagree with is how the user interface would be with CarPlay (with 1 screen). The screen real estate is all used, and in reality, the only area that can be used in the static screen is where the current audio is on the bottom left. See the image below. The right side of the screen is for Tesla's Maps, the left side is for vehicle info. So, in the static view CarPlay would only get the small portion on the bottom left where you can see I have a SiriusXM show on.
Also, CarPlay likes to take over the entire screen, or where it doesn't only a small portion is left for the manufacture's vehicle controls (for example the 12" U-connect screen).
I just do not see how the deployment of CarPlay in Tesla's UI can be successful without taking away from the current awesome UI.
Tesla wants to drive users to using Enhanced Auto Pilot or Full Sell Driving. Because of this, the full screen is used. I apologize, this was the only picture I could quickly find in my phone, the Energy Consumption screen is covering the Tesla GPS maps.
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With the aftermarket clusters that have CarPlay, that makes more sense to me, as it wouldn't interfere with the current UI.