Excellent point about avoiding canned and processed foods! I was at a pizza place recently and decided to save a small piece of pineapple for my glider. I later learned that they use canned pineapple which is not good for gliders. Fresh or frozen fruits and veggies are best.
There are certain foods that my glider prefers cooked, like carrots, green beans, and occasionally broccoli. Others, like peas, she prefers raw. I think either are fine, as long as they don't have any seasonings.