This page: https://creators.vrchat.com/avatars/shader-fallback-system/ describes how the "VRCFallback" tag can be used to suggest to VRChat which shader to fall back to. However, nothing actually describes which shader is chosen for each suggestion; i.e., one of the tags is "Unlit", but there are several shaders with "Unlit" in the name; which one should someone choose if they wish to create an unlit avatar that looks the same before and after shader replacement?

A more general way of putting this might just be: what is the exact list of shaders that an avatar creator can choose, to make an avatar that looks the same before and after shader fallback? The docs mention that "toonstandard" and "toonstandardoutline" fall back to "VRChat/Mobile/Toon Standard" and "VRChat/Mobile/Toon Standard (Outline)" respectively; what do other tags fall back to? (Someone on the Discord suggested that none of the other fallback shaders are available for avatar creators to use; can this be right? Why would it be deliberate for people to be unable to make avatars with the same efficient shaders that the fallback system uses, if that's all they need?)