This is a known difficulty in Commerce 2.x. You can review the options in this issue https://www.drupal.org/project/commerce/issues/2928139
The best solution I have found is displaying row weights in manage display for the product, the variation, and the order item type add to cart form display, and manually set the weights rather than drag and drop.
This won't fix all your problems, but it will help. It really depends on what exactly you want to do.
You can overwrite the twig template in your theme as seen here: https://www.drupal.org/project/commerce/issues/2928139#comment-13444854
You could also hack and hide all the fields, and build custom view of fields, and use display suite to add the block view to your product display.
Sorry there isn't a better solution.