Nah. I stocked up before deployments and stashed it all under the deck plates of my workspace for days when the food from the galley was particularly inedible. But the ship store did have such such items for purchase, and those items certainly sold!

I would have loved if unflavored oatmeal were an option at every meal! I could have saved a fortune on cup noodles and instant mac&cheese!

I can verify personally that this is absolutely false. I remember fondly when the warrant officer onboard would volunteer to help in the galley, and on those days the burgers not only got seasoned, but cooked with the cheese on top! This happened infrequently, but was amazing when it happened.