Having worked on POS software, I can guarantee you we do not have "metadata for products on lock".
Manufacturers will sometimes reuse the same UPC even though the packaging is fairly different. The UPC doesn't contain the price, size, or any size -- it is just a convenient look up for whatever POS the retailer uses, and for systems targeting independent retailers, that might be maintained mostly manually, though some warehousing associations might provide an importable list.
In large retailers sometimes the smart tags are controlled using a system that doesn't even deal with UPCs, just images / webpages, shelf locations, and schedules.
Buyer beware, indeed.