Played around with one of these today (CarLinkIt), and it's more or less working as expected. Kind of impressive: You connect via Bluetooth first, and it uses that connection to auto-set-up everything else, including the wifi connection to the adapter. After the final connection is made via wifi, it drops the bluetooth connection.

Though I have a couple of minor issues, I think the issues are due to my car's headunit firmware being a bit buggy, and not the adapter itself. To be certain, I will need to experiment with switching it between wired carplay and the adapter a few times.