Here's an iOS + Android app that the company I work for makes - it uses OSM as a source, plus proprietary maps for Czech Republic (where we're based). I believ

Here's an iOS + Android app that the company I work for makes - it uses OSM as a source, plus proprietary maps for Czech Republic (where we're based). I believe it has one of nicest and most usable map keys for outdoor navigation: https://windymaps.com/app https://windymaps.com/app