Use a copy of unity API in new thread

I’ve heard that the Unity API isn’t threadsafe, but I’ve been thinking. Since I can define my own class and create an instance and have it run in a thread just fine, why can’t I just create a new instance of the Unity Api for a thread? Is this possible? I’m really hoping there’s a way to do this since calculating meshColliders for procedurally generated meshes at runtime is really slowing things down, and I can’t move it to a different thread(due to thread unsafeness). Would this be possible?

That’s not possible.