osmand+ has a very low cost, one time fee.
https://osmand.net/ Then you download state maps into your phone. So all you need is a view of the sky to get a gps signal -- no phone service needed. It can also do navigation to a destination.
It's very good for trail hiking, when switched to "walking" mode. Lots of local trails are in the map.
The best setup for me is a Garmin for navigation with preloaded routes. And osmand+ for occasionally checking the local map to see what's nearby or decide on an alternate route during a ride. It's very fast to launch, and the maps are very detailed as you zoom in. Garmins aren't good at just browsing a map, they really are designed to follow a course.