You really don’t understand how nuclear weapons work and how absolutely devastating their fallout actually is. Its not a movie or video game where a few survive in underground bunkers and the rest just “mutate”. The fallout from a total nuclear war would wipe out every human life in a couple of decades either through extreme radioactive poisoning or through extreme famine from the irradiation of any and all arable land… Bacteria and tardigrades might survive. Sure as shit nothing else will.