3D Artist Hisakuri, who specializes in 3D models for VRChat, shared a tip on how to "tear" through shapes in Maya. To make the effect, you'll need to follow these (machine-translated) instructions:
Create a blend shape for the shape right before it tears apart.
Create a blend shape for the shape after it has split into two.
Switch between 1 and 2 using Visibility and use the Soft Modification Tool to add rebound movement for the finishing touch!
Yes, it's this easy! How you're going to use it is up to you, but I'm sure VRChat players have some particularly interesting ideas.