There are CarPlay resources from Apple (https://developer.apple.com/documentation/carplay/) but it seems entirely geared towards iOS app development.
Are there any resources or documentation that help with CarPlay integration on the vehicle/head unit side of things? I believe you need to download the CarPlay Communication Plug-In and integrate that with the head unit platform and applications, but there isn't much documentation that comes along with the Plug-In .zip download.
Is there a different place where resources for head unit developers is located?