That's funny, I've just built the same thing for Asda in the UK https://github.com/markDunne/asdabot

It can search for items, add them to the basket, picks a delivery slot and does the checkout.

With a little more scaffolding in markdown files, this now takes care of my weekly shopping.

Even a CLI interface would be better than the sorry excuse of Asda's website. I wonder if entrusting an LLM is worth the trade off with the tedium of online shopping.