That's probably fine. Good luck with the little guy. They don't seem to like crumbs to me. They would eat their food and break it into crumbs at the same time, and leave the crumbs. I gave them bread before I got real food blocks for them. They seem to like rice too. And no, it won't make them explode. Any dry grain should be good for them. Stuff like carrots, lettuce, and apples are good, but they have so much water, they can give it diarrhea.
A piece of bread or a few whole gram crackers should be good for the night or more. They just don't seem to like crumbs from what I've seen.