An offline navigation app that guides you around the world is Maps.me. With this you can easily plan a route, save sights & viewpoints (for later) and it can be used offline. So a nice and good navigation app.
Using this app offline is the biggest advantage, because this costs you no data while backpacking and therefore unnecessary costs. And that makes a difference in the backpacking budget.
Maps.me is for me the app for backpacking especially outside of Europe. During backpacking through Asia I made a lot of use of this. And especially in Vietnam, where I bought a motorcycle, the offline navigation app was a perfect solution. It didn't cost me any data, because I could already download the map of Vietnam via the wifi in my hostels. This way I could plan my route every day with highlights and viewpoints in between in my route from South Vietnam to North Vietnam on the motorcycle.
Offline navigation in Europe You can also use this navigation app in Europe. Especially if you don't have a lot of internet data. For example, you can use it very well when renting a car. Then you can use Maps.me instead of an overpriced navigation option. Or use it during a city trip to walk, cycle or with an electric scooter to all the sights.
Maps.me is free to download for Apple and Android phones