Boxes that food comes in does not touch our food. Our food is usually in sealed plastic bags inside the boxes. Boxes that touch food would more than likely be ok.
My gliders love to play with boxes and I have been known to give them kleenex boxes to play in for a night then remove them in them in the morning.
I also purchase plastic chains from bird stores. They are inexpensive, last forever and can become an interactive toy. My gliders love it when I hang tons of monkeys in a barrel from the chains.
Yard sales, thrift stores, etc are great places to find well made toddler toys for next to nothing. My gliders LOVE toddler toys that make noise. When I put a battery operated toy (make certain the battery is on the bottom of the toy) I hear them playing on it ALLLLLLLLLLL night!! LOL