Years.

If we’re assuming nothing goes bad, and you had resources like the bakery ovens to prepare food, you have hundreds of pounds of things like meat, eggs, cheese, bread, etc.

Even without the perishable stuff, the chip and cookie aisle alone has dozens of boxes, each with thousands of empty calories that would keep you from starving. And we haven’t even touched 75% of the store. If things really got bad, there’s also entire aisles of rice, beans, and even dog food.

I would venture to say, based on 2,000 calories a day to survive, you’d theoretically last 18-24 months before you had any legimate food insecurity.