[coldpie]

Just use a 3.5mm jack. We solved this decades ago.

[dontlaugh]

Not quite, that doesn't allow integration with steering wheel controls.

[rdlw]

Sure it does. Even headphones have controls built in to the cable.

[dontlaugh]

That is not standardised across different headphone manufacturers and often doesn’t work. It doesn’t work at all on cars.

Analog protocols are not a good idea for this. Digital with a decent protocol is much more reliable, whether wired or not. In practice, the best option is either wired CarPlay/Auto or bluetooth.