A notable mention is https://ubports.com/en/ which is different from postmarketos in a sense that ubports uses old kernels with heavy patches. That means: good support for things, but difficult future.
PostmarketOS uses the newest kernels and tries to integrate their patches into mainline kernel, so that the reliability is maintained with all kernel developers.
Phone functionality is the least of my problems, I need an open source replacement for Android Auto / Apple CarPlay.
Not sure how that would work, you’d either have to emulate it to talk to the infotainment system, or get all the infotainment producers to add an open source layer… Sounds like a nightmare either way.
We had the AUX jack but they axed it to sell earbuds.
I have heard that Apple removed the headphone jack to kill compatibility with those Square credit card readers.
And yet here I am supporting people who use square credit card readers with Ipads as one of my job responsibilities… They just switched to bluetooth
That was the purpose of MirrorLink, but I think it’s dead now. I only ever saw Volkswagen support it.