SkeletonUtility is unlikely to be helpful for breaking a skeleton apart.
I think Skeleton Baking is the closest thing we have that's handy for this use.
It will be especially easy if the skeleton in question is not composed of a customized skin but a single one defined in Spine editor.
Right-click on your SkeletonDataAsset's inspector header, or click on the gear icon on the upper right, and choose "Skeleton Baking".
This will open the Skeleton Baking window.
Leave "Bake Animations" unchecked. You probably don't need those.
Choose the skin you want if you have multiple, then press the Bake button at the bottom.
This will generate a prefab with individual GameObjects and MeshRenderers with meshes per attachment.
This baked skeleton prefab is purely comprised of GameObjects and MeshRenderers/MeshFilters without any extra scripts. So you can treat it however you want. Rename it, rearrange its hierarchy, add Physics2D components or whatever other components you want.
At runtime, you can break it apart with your own script by marking specific GameObjects.