Importation of goods made with child or slave labor has been illegal for ~100 years. It is just extremely difficult to track and prosecute. If I buy a product on Taobao, what would the proof of no child labor be? What about the components? Like the battery might be made by adults, but where did the lithium come from? You'd need a paper trial going back to natural resource extraction to keep it clean.

Maybe keep it simple and put heavy tariffs on countries that don't police their own child/slave labor.