But if you use the carplay2air or similar (carlinkit) the connection is by USB dongle and this one connects by wifi with the phone, so the base connection is USB (this is what told me the provider)
That is correct. A third party dongle is degrading the sound quality one can have if one just stays the course and uses a Lightning cable per the process designed by the car manufacturer.
A lot of you are running around trying to solve a problem and its creating more problems. Stay with wired CarPlay and count your lucky stars you have that option. My BMW's have no wired option and it's awful. Very inconsistent wireless connectivity and functionality.