This doesn't quite say they do exactly that, but they do tie location data to offline purchases.
> Since 2014, Google has flagged for advertisers when someone who clicked an ad visits a physical store, using the Location History feature in Google Maps. Still, the advertiser didn’t know if the shopper made a purchase. So Google added more. A tool, introduced the following year, let advertisers upload email addresses of customers they’ve collected into Google’s ad-buying system, which then encrypted them. Additionally, Google layered on inputs from third-party data brokers, such as Experian Plc and Acxiom Corp., which draw in demographic and financial information for marketers.
