If it’s a zombie apocalypse, then I would assume the grid is down. Critics would say that the battery and the durability is a problem, but I don’t think it’s a problem in this time and age. So is the phone really the best source of knowledge during a zombie apocalypse?
A commercial handheld radio would be more efficient, more capable and easier to use than one built with scraps. Still, you cannott download offline maps on a radio