Thank you! I uploaded one of the default VRoid Studio starter models here:
I exported it from VRoid Studio as a VRM file then changed the file extension to .glb. I can then load it directly into audio2face (I had to adjust scale factor to x100 for some reason) but it works and you can adjust joint rotations etc by hand.
One of the reasons I use VRoid Studio is because it means I can create characters without learning DCC tools! ;-) You create characters with sliders and a 2D paint program - pretty easy. I might have a look at the USD APIs to see if I can split the mesh via code (which I would have to do later anyway). But I am still exploring, trying to work out if I can get NVIDIA Omniverse to do what I want, which includes things like hair physics and clothes cloth physics.
I don’t know much about the quality of the assets, only that they work in a range of other applications without problem. I do know if you import into Blender and export immediately, you don’t get the same result (the mesh is modified), which means you have to add any libraries of blendshapes first. So I would not be surprised if they do some “creative” things in the mesh…