I haven’t had any problems taking packaged foods into Mexico. What you can’t take are unpackaged farm products like fresh fruit.
Keep in mind that Mexico has modern grocery stores with most all the same products we take for granted in the US. Also Mexico has large open air markets which are great places to buy fresh fruit and other products.
If you are going to climb from the hut there’s no reason to restrict yourself to dehydrated food. You may as well have things like bread, cheese, packaged meat slices, produce, pop, chocolate milk, potato chips or whatever.
The biggest logistic will be when you buy this stuff during your travels. When I did Orizaba in 06 we hired private transportation so we just had the driver stop at a supermarket. If you are travelling by bus with gear, then it is more of a challenge to figure out when and where you will buy supplies.