no rooting necessary, you install one of these apps and you start using osMaps ☞
- https://f-droid.org/packages/net.osmand.plus/
- https://f-droid.org/packages/app.organicmaps/ or https://github.com/organicmaps/organicmaps
organicMaps is simpler, easier to use for navigation. OSM+ is more customizable with lots of options and modes to choose from
to contribute easily ☞ https://f-droid.org/packages/de.westnordost.streetcomplete/
they are probably available on playStore too but you wrote you wanted to degoogle
edit:
"uMap lets you quickly build custom maps with OpenStreetMap’s background layers and integrate them on your own website." ☞ https://umap-project.org