Is there a way to modify ModelEntities loaded from an .usdz file on a node basis? E.g. show/hide specific nodes?
Yes, if you load the USDZ with Entity.load(...) or Entity.loadAsync(...) you can traverse the hierarchy and modify the individual entities.
You’d want to use Entity.isEnabled in this instance to hide/show a node.
Note that .loadModel will flatten the hierarchy whereas .load will show all entities