I use maps.me, and there are several user-contributed walking trails.
For unmarked trails, I draw a few trails using Google Earth Pro, and export it to maps.me, which will then draw the waypoints and trail on the map. There are communities like GPSies that share similar trails as downloadable KML files.
I use an Android phone with 6" screen + 5,000 mAh battery, accompanied with a 20,000 mAh power bank. With music playback for 7-8 hours, and occasional maps use, it's good enough to last 5-6 days in airplane mode.
I use an Android phone with 6" screen + 5,000 mAh battery, accompanied with a 20,000 mAh power bank. With music playback for 7-8 hours, and occasional maps use, it's good enough to last 5-6 days in airplane mode.