Though reading the specifics there, it looks like Google's adapters in particular should work with any other phone because they can handle analog or digital signals. So they're doing well.

Other manufacturers are doing... less well.

Google's adapters can work on most phones, but Google's phones can't work with most adapters :-(

It's unfortunate because it's the "USB-C standard" not to do analog through the pins, but I think this a case where it's ok to break the standards. I'm not sure if there are any IEEE fines for that though.