It looks as if I can use the Multi-Peer features of Arkit with my Unity project to be deployed on iOS. Apple states in its example that Realitykit is only the renderer and ARkit handles the multi-peer. Should I assume that since we are already using ARkit in our Unity project that we would make the calls for collaboration within Unity?
Yes you can do that. Try this repo https://github.com/Unity-Technologies/arfoundation-samples/tree/main/Assets/Scenes/ARKit/ARCollaborationData.
But in order to use MultipeerConnectivity in Unity, you will need a native Unity plugin for that.