As I antcipated that even running the latest version of my car’s (Suzuki Swift Sport) informatinment system (Bosch branded unit) firmware doesn’t resolve the issue with the Phone 2a and AA, other devices work fine.
So it’s definately an issue with AA, the Phone 2a and some compatibility with some cars infortainment units (as people have mentioned it works fine for them, though have call issues).
Hope Nothing can fix this via an OTA software update in the future (people already mentioned that support have mentioned to them that an upcoming OTA update is coming). I have advised Nothing support also and will be keep an eye on future updates on the issue being resolved, but until then back to a Google Pixel.