I have had a large onion bag of black walnuts for about 15 years, still good, just do not shell until ready to use.Nuts are half or more fat/oil by weight. They tend to high omega-6, but there are some nuts and seeds with good omega-3. (Walnuts are the nuts with the most omega 3; hemp, flax, and chia are good seed sources.).
They are excellent sources of good oils and essential fatty acids as well as a number of other nutrients, which is why it's now recommended to eat an ounce of them a day. However, like all oils and very oily foods, they don't have a very long shelf life. Oxygen absorbers and a freezer may get you a few years, but 1 to 2 is the outside on a shelf.
If you have land, plant nut trees.