Apply Rotation only from Matrix

Referring to an old (seemingly untouched) issue: Object3D: localToWorld/worldToLocal for quaternion and scale? · Issue #13704 · mrdoob/three.js · GitHub

I would like to transform a vector into the local object’s rotation. Object.worldToLocal(vector) also applies position and scale, as expected. So the question is, what’s the best practice to apply only rotation?

Matrix4 has an “extractRotation” function, but having the rotation alone still doesn’t help further.

Thanks for any help