Remove Optional VM Interfaces

[joshua-kim]

It's not clear why we used optional interfaces, but this pattern is extremely confusing + makes development of generic types on VMs difficult. Some ideas to remove this include making these optional interfaces required, and just returning sentinel error types if they're not supported.

[github-actions]

This issue has become stale because it has been open 60 days with no activity. Adding the lifecycle/frozen label will cause this issue to ignore lifecycle events.