You can use a VRM with no mesh so it's invisible!
Viewing post in Twitch Integration For Avatars comments
You can take a sample VRM from https://github.com/madjin/vrm-samples, delete the mesh in Unity and re-export it as a new VRM.
You can take a sample VRM from https://github.com/madjin/vrm-samples, delete the mesh in Unity and re-export it as a new VRM.