I can vouch for the strawberries. I started with only about nine plants and now they are a huge mound and threatening to take over the entire side yard!
Several kinds of strawberries produce fruit twice a year (Spring and Fall). That’s a nice feat for a perennial that you never have to plant again.
Twice a year you’ve got new food being grown into your supplies.
Realistically, you can’t really store enough food to last you forever, but you *can* grow it.
Strawberries cover your Spring and Fall.
Add one male and one female arctic kiwi perennial and you’ve got Winter covered (kumquats and persimmons work for Winter, too). A single little female arctic kiwi vine can produce up to 120 pounds of kiwi fruits per Winter! Such vines can grow on fences and the sides of buildings to make use of wasted space, too.
*male+female species like kiwis require cross pollination with each other...if chemicals/warfare knocks out all of your bees and butterflies you will have to hand pollinate them (easy enough) or hope for air pollenation (much lower fruit production).
Then you just need a good Summer perennial like Apples (blueberries, blackberries, or cherries) to keep you supplied with food year round, forever and ever.