I have an insulated shipping container; at my last farm the mice chewed out the insulation and moved in. On this farm, been 5 years or more I haven't seen any rodent damage yet, and store grass seed and other seeds in there and haven't seen any issues.
I did store feed in it at the previous farm but haven't since the rodents were getting in and out of it.
Otherwise the container is great for storing all sorts of things relatively free from dust, insects and other animals and big changes in environmental temperature. I use dehumidifying crystals, avoid opening on wet days, maybe do open and supervise open door (cats and chooks can get trapped unseen) on a dry sunny day; our normal environment is 60 - 70% humidity and can damage paperwork and anything else susceptible to moulds, algae, damp &c.