I cannot find a combination of settings to allow me to listen to music from roon on my AirPods on either my Mac or iPhone. no error messages just silence aurpods work fine using tidal on both phone and Mac.
Are your iPhone and Mac seen as endpoints from the Core? You should be able to set the System Output of the Mac Roon Core as an endpoint, and if the AirPods are connected to the Mac, the AirPods should play that selection from Roon.
Similarly for the iPhone, if the iPhone is seen as an endpoint and the AirPods are connected to the iPhone, Roon should be heard through the AirPods if the iPhone is selected from Roon.