This!! Those pre-cut fruit bowls at Publix are the FIRST thing to go in my cart. And then their mini muffins, probably.
If we start over at Universal, then we'll pop into the Whole Foods over that way. They don't have the best selection of bottled water, but the prepared fruit is great! They also have a lot of prepared foods. One that is kinda unique and really good is the fully prepared key lime shrimp, now over by the seafood dept. They are chilled, and marinated in key lime oil w/garlic. WF is not inexpensive, but they have a large soup/hot food/salad bar area, pizza, and more. It is also a decent place to pick up something like a birthday cake.
A classic travel problem is not having a knife to cut fruit. I do like that WDW now has tangerines. They are much better than the Sunkist oranges. There used to be an orange stand up on 192, but it was just so-so, and the FL oranges have been hit hard the last few years.
Another plus of a grocery run is good yogurt.
If we start at WDW, then Publix is one place we also shop. I can make do though with Target.
It can also be helpful to place an order for pickup. Just be aware, if the Target order contains perishables, then they only hold it for like 48 hours, I think.
Last year, we arrived late, and I tried a company that delivered direct to our hotel. It was a little pricey, but the order was great, and nicely packaged. The biggest downside was a somewhat limited selection. Otherwise, I'd use them again.