If we create a SystemExtension using the Endpoint Security APIs, how can we communicate with another process? It looks like for a NetworkExtension, the NE framework will setup a Mach service on your behalf using the NEMachServiceName Info.plist key. I don't see anything equivalent for a plain vanilla system extension.
Since the system manages the lifetime of the SystemExtension, and its location on-disk is embedded inside an application, you can't register for a launchd-managed Mach service yourself.