Audio Server Plugin entitlements and communication

I am currently working on planning a multi-component software system that consists of an Audio Server Plugin and an application for user interaction. I have very little experience with IPC/XPC and its performance implications, so I hope I can find a little guidance here.

The Audio Server plugin publishes a number of multi-channel output devices on which it should perform computations and pass the result on to a different Core Audio device. My concerns here are:

  1. Can the plugin directly access other CoreAudio devices for audio output or is this prohibited by the sandboxing? If it cannot, would relaying the audio data via XPC be a good idea in terms of low latency stability?

  2. Can I use metal compute from within the Audio Server plugin? I have not found any information about metal related sandboxing entitlements. I am also concerned about performance implications as above.

Regarding the user interface application, I would like to know:

  1. If a process that has not been started by launchd can communicate with the Audio Server plugin using XPC. If not, would a user agent instead of an app be a better choice? Or are there other communication channels that would work with sandboxing?

Thank you very much!

Andreas