On the Sync 3 vs Sync 4 debate:
FWIW, you can make Sync 3 be wireless using this device.
Carlinkit 5.0 2air CarPlay Wireless Adapter,Android Auto Dongle-Latest Release,for OEM Wired CarPlay and Android Auto Car,Auto Connect, OTA Update,for iPhone and Android,via Plug-in USB Connection
https://a.co/d/ioQVn5U
I use them in all our Sync 3 vehicles and it does the job. There is a section where you can adjust the media latency (the delay from your phone to the unit) and you can go as low as 25 ms of delay so its *almost near what native wireless car play is now.
I did mess around with a newer APIM module capable of Sync 4 and got some things working but ultimately the dongle with the media latency ended up being the best solution.
We started using the same dongle in our ST and I’ll admit, with the larger screen it’s weird. It puts CarPlay on the top half with the radio on the bottom half. I’ll have to look into the settings again to see if I can make it go full portrait. But as is, works almost as well as having native CarPlay.