UMaterialInterface* MeshMaterial = HitComponent->GetMaterialFromCollisionFaceIndex(MatHitResult.FaceIndex, MaterialIndex);
You are better off cracking the source code and lifting that precise function to repourpose it.
Also, since it uses a parametrized material you could potentially create a material to use as the parameter.
Still, if apples and oranges are the same, the UVs are the same, and the hit face therefore matches the texture pixel(s).
You could probably just return the correct physical material color/value off a comparison without having to re-run the function or deviate it further.
Then again, assuming your physical material mask is assigned and implemented correcly on the mesh itself, the HitComponent will already return the physical material for you.
And because of that I’m unsure of what you are attempting…
Also, don’t make the asaumption that “other” things you hit won’t have a physmat mask assigned. Its very possible they could. Even on skeletal meshes…