This was just added in the latest version (2021.01.27). It might only be available on the Dev Branch right now.
Creates bone followers based on the current entity model.
Bone followers are physics objects that follow the visual mesh. This is what is used by
prop_dynamic for things like big combine doors for vehicles with multiple physics objects which follow the visual mesh of the door when it animates.
You must call Entity:UpdateBoneFollowers every tick for bone followers to update their positions.