This exists in india already

The food delivery apps (zomato, Swiggy) support "agentic shopping" through an MCP server.

You can reserve a small amount of money in UPI apps that doesn't need any approval to be debited (only by a specific merchant).

Razorpay which is a payment gateway has an MCP server

So you can add razorpay in your app, and claude can pay.

Claude can access the Swiggy MCP server and search using natural language there.

The incentive for the food delivery app to participate in this is better targeted ads.

I highly doubt that a consumer would see any financial benefit from this. Sure different grocery stores use different products as loss leaders, but the trade off is time, so rather than the cost of having one person go to one store and by X number of items, we're sending either one person to three stores for ~X/3 items, or three separate people to three stores. All of which will take more total time than 1 store, which puts more resource demand and will cost more to the consumer.

Also, it would rather be in the faceless ai shop's interest to arbitrage orders, always show the "middle" price but use the cheapest one for orders.