> the carplay experience fights with the car OS constantly and is an awful incoherent experience.

It seems to me like fixing this is the appropriate path forward. There are things that the car OS is better at (like you mention), but no car OS is ever going to support the various media apps I have on my phone that are automatically supported by Android/Android Auto media controls, and bluetooth playback is an even worse experience than cludging together the car OS + android auto media in one UI.