I like where this is coming from but I'm afraid it's totally backwards. Apologies if coming off as unfriendly.

I picked a spot on the map and no store within 25 blocks in any direction has any deals. That's fine, and it's not the author's fault that they don't publish deals, but after that the next thing to do is to search for a particular thing. If you live at that point on the map, is the rational thing to then go to another borough to save a dollar on tofu?

I think most people look for grocery deals opportunistically and if it's not where they are then it's not interesting. The question isn't "where's the cheapest X", it's "what's cheap near Y".

I don't think there's a good way to do that either without sharing device location. I asked the bot "what's the best store near St. Patrick's Cathedral?" and it hadn't the faintest idea, even after multiple follow-ups.