Since then, I’ve come to the conclusion that this probably can’t be done directly in unreal. I’m no expert but I believe the data in the vertices/faces themselves have blend weights which are mapped to specific bones, so removing bones would probably cause some unintended consequences when it comes to animations (openings in the seams of the mesh or clipping).
Also, in my experience, parenting a Metahuman mesh to a simplified armature with automatic weights in Blender usually doesn’t work out of the box and a bit of vertex painting must be done in order to not have serious animation issues, such as having a bit of the mesh’s heel stay in place during a running animation, causing a big stretch in the vertex. It is a huge hassle anyways for a non-3D artist hoping to use Metahumans as a way to bridge my inexperience.