Hi,
That's not something we can do for the short term. The big issue is that it's not only about the products selector in the backend, but it's about the fact that the fields for refresh automatically based on the selection of the variant on the product page, the checks on the server side should be done on a per variant basis, and that introduces issues with the custom fields being displayed on the products listing where you can't select the variant. So quite a lot of things will have to happen to be able to do that properly.