We can capture session events (namely anchors add/remove) by implementing ARSessionDelegate (not RealityKit), is it possible get similar or part of this events with RealityKit? (To avoid converting a from ARAnchor to AnchorEntity)
RealityKit exposes the ARSession through this API:
https://developer.apple.com/documentation/realitykit/arview/session
You can set the delegate on it to listen to ARKit delegate events.