This is the first thing that popped up when I searched for "millenium bar." No wonder it's as hard as steel -- because it is steel!

https://inward-scooters.com/products/ygw...awaApqTEALw_wcB

I agree with Phaedrus on Datrex. I did a taste test and it was like a coconut cookie to me. It seems like different people have different reactions to this type of survival ration, though, so your mileage may vary. But stuff like Datrex is just calories, with little nutrition. That's a downside.

I'd recommend that doing more than taste-test -- do stomach test of some of the foods for a day or two, and see whether your body tolerates it, and how well you can perform with that kind of fuel.