I suspect that there are other jars somewhere, but I guess the seller is engaging in just a little bit of hyperbole. KraftHeinz is still making pickles under the Claussen brand, although those are strictly sold refrigerated. There is a Heinz Ave near me. I visited on a chocolate factory tour there years ago, and it was explained that it was where Heinz had several factories. Heinz must have had multiple production locations around the US. The building for the chocolate factory was where Heinz made pick;es.
Last jar of Heinz Genuine Dill Pickles on Earth

US $20,000.00
or Best Offer
Item description from the seller
This is the last jar of Heinz Genuine Dill Pickles on Earth.
Heinz discontinued making them.
This jar was purchased from the last batch Heinz distributed.