Two of my most-watched videos were about prepping items with an indefinite shelf life. I think they hit home because nobody wants to buy something, forget about it, and find out it went bad right when they needed it.
Here's the short version: honey, salt, distilled white vinegar, high-proof alcohol, baking soda, cornstarch, sugar, activated charcoal and bentonite clay. And a bonus, real vanilla extract. Buy them once, store them cool, dry and dark, and they'll be there.
Why these, and not just food
Every one of them does more than one job. Honey sweetens your tea, but it also soothes a cough and makes fermented garlic honey. Salt preserves food, scrubs pots and makes a saltwater gargle. Vinegar cleans, pickles and softens laundry. That's the kind of item I love in a stockpile.
A few honest notes
Sugar will cake up over the years. Break it apart and use it. Honey will crystallize. Warm the jar in water. And for disinfecting, you need strong alcohol, at least 60%. Regular vodka is great for tinctures but too weak to kill germs.
The full list, with every use and the safety notes, is on my Items that never expire page.