Here are some additions to 3prettyprincesses list.
cinnamon pecans are safe too
pineapple fruit bar
tri-coloured popsicles
Enjoy Life products (cookies & chocolate bars)
OMG It's Gluten Free products (cookies & brownies)
Babycakes products
Disney brand potato chips
a bunch of the bagged Goofy's candies are GF; they're clearly labelled so just read the label to be sure
Minnie's bake shop has some GF cookies though I'm not sure if they have packages small enough to be bought with a snack credit; they have other things we're allergic to so I've never asked
frozen Coke
ice cream sundaes
kaki gori
I know there's other stuff but I'm blanking on other things right now. This is more than we can have due to other allergies. I know there are others that we can't have that somebody who's only GF can have. I don't know if LeFou's Brew can be purchased using a snack credit or not. I don't know if those frozen red, white and blue treats in the American pavillion are GF or not but for some reason I'm thinking they are. I think the frozen chocolate covered bananas are GF too.