[djdeutschebahn]

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

Related thread on hn: https://news.ycombinator.com/item?id=37533633 But didn't took of.

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