>>270897558
I've seen moth girls with several arms and centaurs with four legs, both animate properly and follow your limb movements. The extra arms bit is fairly common though most are big mechanical things that float behind and around the main model. Couple of monsters but they generally don't animate with vr controls and just have animations on gestures. Some have tentacles weighted to arms.
You can do a lot but it's just the way vrc and the vr component works that it requires a human skeleton to animate. It doesn't have to have any part of the mesh weighted to those bones but it won't do anything when you move in vr if those bones aren't present and configured in the right way.