Ooh, that's a great question. I'm not aware of that being an option yet, in order for that to happen there would need to be a material editor functionality—which there is a basic one in reality converter—I'm honestly looking forward to a more robust material editor within Reality Composer. I feel like once that is in place (or if Converter accepts video textures) then you'll probably see that kind of functionality. Please do share if you get that figured out! 🙏

Reality Converter accepts .obj, .fbx, and .usdz files. As long as your .obj/.fbx/.usdz files are in the same folder as your materials (and they are named correctly) it should automatically attach the materials to the model. I've found that the preview doesn't alway show in the main 3D viewport but as long as it's showing the associated textures on the materials panel you should be good. If it still doesn't work I've found that if you open the .usdz file into xcode then save it and switch back to Reality Composer that it fixes it. In order for Reality Composer to accept .fbx I think you still have to download the FBX python sdk which can be found on autodesk's developer network (just google FBX python sdk). Also, there is a plugin to create usdz inside of blender https://github.com/robmcrosby/BlenderUSDZ

I'm not sure if this is from the latest version but I noticed that on Mac OS that .reality files work in quicklook (spacebar) preview window. Touch points work onClick but seems like you have to click twice in order for it to work. I haven't tested any sounds yet. Side note: I find it odd that you can't export a scene from RC (on mac OS) as usdz but you can from iPhone and iPad.

correction: RC exports out a *.reality file that's like 25kb.