What 3d model formats are supported by RealityKit and SceneKit frameworks?

I know that USD is the main file being used for ARKit development. I'm pretty sure that you cannot view things like fbx or obj in Apple Quicklook, so they don't support those unless they've been converted to USD format.

Reality Converter makes it pretty easy to do that but there are some issues with UV's (when trying to convert fbx to USD) that I've run into which makes my workflow more complex. For my project we create an FBX in a tree modeling program then convert it to a GLB through a Maya plugin and then convert that GLB to a USD in Reality Converter. That's how we've gotten around the UV issue in Reality Converter, and there are still some other issues that come up during conversion.

Hopefully Apple starts putting more resources into the ARKit stuff so some of these issues get resolved.