Great review, it's hard to hear about what doesn't work, which you summarized nicely.I got UNAVI installed on my 2019 Infiniti QX60 installed, and here is what I found, not sure if it's expected or not. 1. Dashboard control button doesn't work, you have to use the touch screen. 2. Change volume will displayed on the carplay screen which is good, I am not sure why it doesn't shown in this video, but it works for me, however, the AC is not shown, you can still use the Climate button to turn on/off AC while in carplay mode, but nothing shown in the screen, meaning you don't know the temperature or fan speed etc, you have to change to OEM UI to see it. 3. Wheel steering control partially working, you can change the volume up and down, or next/previous songs, but the return button doesn't work, I meant doesn't do "return" function, it only works to switch between OEM and carplay mode while you hold it for 3 seconds. Hope this helps to anything who interested in UNVAI.
I've heard from previous posts some OEM functionality doesn't port to the Carplay screen. Users get used to this, saying you'll get comfortable switching back/forth between screens. Did you reach out to UNAVI to ask about missing/lacking functionality, to ensure it was installed correctly?