Make sure you import ARKit at the top of your swift file, the different AR configurations aren't included in just RealityKit: swift import ARKit

+1 for attention to finer but much needed detail like this please! Or just being able to set blend modes if that's the issue.

Not with the builtin MultipeerConnectivityService, but you can always encode your own data to then send over a TCP connection to another device. The collaboration data can be grabbed with session(_:didOutputCollaborationData:) - https://developer.apple.com/documentation/arkit/arsessionobserver/3152999-session then sent over your network instead. I think if you go to any further detail then you'll need to create your own data structure for sending instructions between devices, which is certainly achievable.

In RealityKit the animation will always take the shortest path to get to the correct transform. This means that rotations will take the shortest distance. If you want to force the animation to go the other way around you'll have to add two animations in sequence: the first one goes half way round the anticlockwise direction, and the second is the final transform of your entity. This also means that you can't spin around an axis object continually without doing something similar - which is very annoying!!

Since iOS 15 / macOS 12 we can now add shaders in RealityKit 🎉 The entry point for these is GeometryModifier and SurfaceShader. The usage of these is used in the Underwater code sample: Building an Immersive Experience with RealityKit

Sounds like you might want to change the properties in PhysicsMassProperties for your object when it's in dynamic mode, maybe your impulse isn't big enough.

Try using HasModel instead of ModelEntity. Your best bet at solving this is putting a breakpoint after setting map and having a look at the contents with Xcode's inspector.