We tried Celebration town Tavern some years ago. It was very good, but it did take us a little while to eat there.
We are also often on the lookout for fresh fruit, and find WDW lacking in this area.
More recently we have had decent food from Miller's Ale House. The one near Disney Springs is better than the one up on 192. (there are 2 near WDW.) We specifically were looking for late night food. If you want to eat after 10pm, not much is open on WDW property. Miller's is a chain, and pub food, so not all that exciting, but decent for burgers. We did curbside pickup, and the food was ready when we arrived. It was a short drive. I don't know about fruit, but one of the side options is real veggies. (close, offsite, fast)
Another similar offering is CityWorks in Disney Springs. They have a broader menu, but also pub food. Also great with call-ahead orders. (close, speedy, decent inexpensive). If you join their rewards club you get a coupon for $10- but you might have to eat there twice to use it.
If you want fruit, and will be visiting very soon, winter is citrus season. Up on 192 is a citrus stand that looks like a giant orange. The FL citrus groves were BADLY damaged by storms last year, so this has been a rough year. It is also important to know that citrus season only lasts until like April. Right now is really the peak of it. The farm stands have fruit in summer, but it is not nearly as good. (close, fruit, quick)
If you are visiting Universal, there's a great Whole Foods over on Sand Lake Road. If you are coming from the airport, it is not too far out of your way. It is a big WF with a fresh juice bar, in-house pizza, smoked meats, bakery, etc. they have a giant salad bar, a giant hot foods bar, and lots of hot soups. Not close to WDW though. (quick, lots of FRUIT, not close, everyone gets what they want)
In Disney Springs, maybe try the frozen gelato. not fresh fruit, but they have gelato in fruit flavors that are very fruity. If you happen to be driving, and going near St Augustine, try the fruit bars from the Hyppo! Lots of unique flavors! Made with high quality fruit! (though also not close to WDW).
Flamingo Crossing has some new places to try. One place that has not yet opened is Lime Fresh Mexican. Website says it will open 'soon.' I don't know it is quite what you are looking for, but it checks some of your boxes. We went to one in Tampa, and it was very good if it opens in time for your visit. They had a fresh salsa bar, and I recall their food came with lots of fresh tomato and corn. I hope the new place is just as good. There are several other places that are quick serve chains. I don't know any jumps out as exceptional, but they are new. Firehouse Subs is one, and Pieology Pizza is another. (about 15min from the parks, prob16-20 from Bonnet Creek.)
Disney Springs has Blaze pizza. For a fixed price around $11, you make your own personal pizza, and choose all your own toppings. They have tomato and pineapple! At a minimum, everyone gets the exact toppings they want, and your son can choose from assorted produce. In addition to pizza, they have salads, and again, each person chooses toppings, but most people get the pizza. The pizzas are pretty generous. We usually coordinate/share and get a salad to share. Sometimes we make 2 meals from the pizzas. (close, inexpensive, custom, quick)