I was here long ago. I don't have too much free time for projects like this. I have no idea how long will it take...

I bought the parts long ago, more than 1 year. I did not touch them since then.

The main problem is with the first project that I cannot handle phone calls at all. I did not find commands for that purpose via cable connection.

I found an android application (called JVC Smart Music Control), it connects to the car audio and can control it via bluetooth. It can change the volume, change the tracks. I think I can use it somehow.

Next step was to enable the developer mode on my phone (Honor 9) and enable HCI logs. Unfortunately there is a bug in the software so it does not generate HCI log at all. (I reported this bug to Honor already). Then I switched my old phone (Nexus 5), enabled developer mode, switched on HCI logs, connected the phone to the JVC and then saved the HCI log :) You can open it with Wireshark.