I guess there is nothing that prevents me from doing things like saving Entities to a global var or something similar, then acting on them in the .onChange(of:) code.

Yeah. the way it hands me the RealityContent only in certain closures lead me to believe that somehow it was a transient object that I couldn't rely on being the same from frame to frame. After digging through some samples like Happy Beam, I realize that, no, they are just convenient places where I can grab stuff important to me. It seems the only thing I need to worry about is that I am responsible for releasing my hold on any Entities I might grab. thanks for the confirmation

Thanks Michael. Knowing that I can't do it (yet) is helpful. I'll file a request.