Hmm, for me that sound like the normal way customs declaration a made machine-readable. Every shipment already includes a label with a code including the customs declaration.

On each shipment, there would be only one label - not a barcode for each different product.

And I found this statement:
"Standardised Manufacturer PID (S-PID): A global barcode like an EAN, UPC, or ISBN. This is mandatory if it exists. If your product does not have a global barcode, you must write "NO" or use an exemption code"

If it does not exist, you write "NO" - not pay to get one.