It's currently limited to just Pixel and Nexus phones.
Updated 5/17/18 — Since issuing its press release at I/O, Kenwood was told by Google that it's "working with several smartphone manufacturers to bring wireless compatibility to devices with Android 8.0 OS. According to Google, this compatibility will be available on select non-Google smartphones soon."
In mid-April, Google finally launched its wireless mode for Android Auto that was announced back at CES in January.
The feature's currently exclusive to Pixel and Nexus phones, but later this year, it will open up to many more people.
According to a press release issued by Kenwood –
For other manufacturers, wireless Android Auto will be implemented with the adoption of Android OS 9.0 or higher.
Google previously noted that it was "actively working" with other OEMs to bring Android Auto's wireless option to more devices, and rather than having to wait for individual brands to be supported, it looks like any phone running Android P or higher should work just fine.
Wireless Android Auto enables you to use your phone to power a supported infotainment system in your car with the Android Auto interface without having to physically plug in your phone. It's a pretty slick setup, so it's exciting to see that more people will get to join in on the fun once Android P's officially released later this year.