I guess I’d say first that I don’t have anything on hand to do that with, and I have a lot of shop and garden tools.
If you can turn a skeleton into powder, it’ll no longer be recognizable as a skeleton. It has nothing much to do with composting though. It’s debatable whether the powder would undergo any chemical change by microorganisms. Eggshells for example go into a compost pile and ride along into the soil eventually where they make minerals available to plants, but eggshells don’t get significantly broken down by the composting microorganisms.
Yes, soil additive, not composting material. That’s all I meant. I think the original question was could you compost a body and I said yes except the skeleton and then someone asked what if you grind it up and the answer is still you can’t really compost bone.