I do have a house full of old Android phones, lol. Rather than piling up in a drawer, a while back I re-purposed them into IP phones and keep one in each room. I suppose I could part with one haha.

There are some offline map programs that work well, but I’m not sure if the routing works offline or not. I did learn recently that many contemporary “dumb” phones can do wifi hotspot, so that’s always an option if I do need to give it internet for navigation.