There is no way. If it takes 30 minutes for a customer to shop for their groceries, it takes the same, if not longer for a shopper to shop for them. They have to go around to all of the aisles and pick out all of the items and put them in a cart, the same as a customer. Except if they are out of a specific item, the shopper has to text the customer for a replacement. Customers aren't always timely in their responses. So you would have the same amount of human hours of shoppers in each store as you would if the store has customers. Once they shop the orders, where do they put the groceries? They would need a huge amount of refrigerated and freezer space at curbside. They would need a large group of people to pick out the refrigerated stuff and match with the other stuff at curbside and take out to the cars. How many curbside spots are there now, like 15? You would need to increase to like 100.
What they need to do is restrict customers to one person per family. You shop by yourself. This would cut down the number of people in stores greatly. Shopping should be an essential activity, not a social activity. I also like the idea of males can go every other day, and females can go every other day. Stores also need to do better in forcing people in the lines outside to stand 6 feet away from the person in front of them. I saw a picture at a walmart where they were using carts to make spots for people to stand 6 feet away from others in line.