I don't think Amazon supports queries across multiple search indices. However, there is a special index named All that you can use with UPC lookups.
Look up UPC and EAN Codes and Information
Item Lookup. Instructions. Enter the all digits printed on the UPC bar code, including any numbers to the right or left of the bar code itself, even if they don't
UPC Barcode Search is a Universal Product Code Search Engine. UPC lookup for a barcode database of over 2.5 million products.
Enter the all digits printed on the UPC bar code, including any numbers to the right or left of the bar code itself, even if they don't line up completely.
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Walmart Upc Codes Lookup at Website.
For a Walmart UPC code lookup you will need to enter all the digits printed on the UPC bar code. You can also look up the UPC code with the name of the product.