ALL of the internationally branded phones i’ve had (mostly chinese) had compatability quirks with my aftermarket jvc head unit.

I would suspect GrapheneOS would be more likely to work than these, but you could always ask on the forum if anyone has any experience

TBH I don’t remember if it was wired or wireless but my understanding is that GrapheneOS’s implementation is essentially the same as what is included on stock android for Pixels, so both wired and wireless work (https://grapheneos.org/usage#android-auto).

I used it with a stock system so not aftermarket. Do you have any specific reason to believe aftermarket systems wouldn’t work? If they support android auto you should be fine.

If I can answer any questions about GrapheneOS lmk. Android auto works, I don’t drive much but I’ve used it before. You can also ask on https://discuss.grapheneos.org/