I can’t recommend a hand crank flashlight… moving parts, low cost, and reliability aren't a great combination. If the dynamo fails you have no light.
I would also advise against looking at runtime as your primary deciding factor. Truly efficient current-regulated lights are expensive. Many cheap single-AA LED lights don't limit current at all, counting on the limits of the battery to avoid overdriving the LED. Running lithium primaries in them may kill them. Alkalines love turning into a crystalline mess. Neither is what you want to discover in a tornado shelter.
But... if you can find a cheap single-AA light that uses a simple resistor to limit current, you're golden. Buy four and stash them away. They might be inefficient but you can make up for that inefficiency with extra batteries that are proven reliable in adverse conditions and are still at reasonable cost. A 20 pack is ~$37 and you only have to buy it once every 10 years. If you need more than the 40 or so hours that would provide, I would consider a different battery type.
Good luck in your search