OpenStreetMap does
not provide native apps, but there are plenty of (navigation) apps that provide routing based on OpenStreetMap data, my favorites being
https://www.magicearth.com/ for car navigation,
https://cycle.travel/ for bicycle touring and
https://organicmaps.app/ for everything else (also completely offline).
There’s a bunch of different apps to use for bunch of different use cases: https://wiki.openstreetmap.org/wiki/List_of_OSM-based_servic...