Around the Acropolis and within walking distance there is enough to do and see to keep you busy for a week. It will therefore be a problem to find other activities after the ones you have planned. It all depends on your preferences.
As for food shops, I don't see what you are referring to. The inhabitants of Athens eat and drink like everyone else, so there are food shops everywhere, from the small grocer to the supermarket, butchers, fishmongers, fruit and vegetable sellers, local markets, etc. .
The most interesting would be for you to go to the large municipal market of Athens located Athina street but you have to go there in the morning.
https://maps.app.goo.gl/aHgV1BpdiQ9uzdLY6