We use our Samsung android phones (j7) and a 7 inch samsung tablet for all our navigation - magnet mount on the windsheid. We have a plethora of other electronic devices, a 10 in tab, laptops etc. All our maps are off line (downloaded onto our devices) We have Vodaphone sim cards for internet data and phones (Italian account) and now Europe wide with the new roaming regulations from June 2017.
Offline maps (driving, hiking, cycling, and being tourists) Osmand