There are a number of 24hr Walgreen's in the Orlando area. Walgreen's are all over the place. I know for certain there is one on I-Drive (that's 24hr). There is also a Walgreen's near the Gaylord Palms (not positive if it's 24hrs or not).
Walgreen's is fine for some minor snacks - like cereal, water, milk, chips. They won't stock lie a grocery store, but the prices aren't too bad for some items like that. We got a great deal on bottled water there a few years ago. They also had a pretty good selection of travel sized toiletries and things like travel sized laundry detergent the last time I was there - and that was before the current travel madness.
Walgreen's isn't my favorite pharmacy in the world, but it's a quick in/out for the kinds of itmes you list.