If you have space and stable temperatures, canned goods off the shelf at the grocery store will last 20 plus years. Freshness dates on canned goods are completely arbitrary, solely to satisfy federal regulators.
That takes care of the water for rehydration issue.
Agreed - mostly. Canned tuna goes bad around a year after the expiration date, and you know it as soon as you start opening the can. I don’t even experiment with keeping fish past its best by date any more because of the smell when it goes bad.
Other foods may last several years past the label date. Canned fruit does very well, and I’m testing to see just how long, but it’s at least three years beyond the labeled “best by” date. Tomato sauce gets a metallic taste by two years after the label date, but it’s still okay.