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I find these types of maps fascinating. For people wondering what would this map look like if we were not limited to the USA and Aldi: https://www.numbeo.com/cost-of-living/gmaps.jsp?indexToShow=...

There are a few larger categories (groceries/rent/etc.) rather than individual items.

There exists data for websites of groceries in german speaking countries. But I think without location coordinates of each supermarket.

This one tracks all online prices of all the austrian grocery brands https://github.com/badlogic/heissepreise

They also gathered some historical data and competed with an government initiative to establish a price comparison app.