As an extension to this: https://vrchat.canny.io/feature-requests/p/allow-uploading-your-own-animation-controller-for-humanoids and https://vrchat.canny.io/feature-requests/p/custom-animator-controllers-on-humanoid-avatars

But you can use keys to control your character in more ways. I remember you were able to do this using VRC_KeyTrigger, but that has since been deprecated.

This would greatly help out desktop users with more control over their avatars and VR users use the extra bones not used in their humanoid rigs.