Openstreetmap (OSM) is a much larger project than you seem to realize. At least OSMAnd is “theirs”, and there is many apps/sites/software that use OSM behind the scenes. E.g., all the official route planners of cities in my country.

And if you REALLY want to help, openstreetmap has very good tools for adding information, though you need to use the website for it since it can get quite complex which makes it a bit more cumbersome.

Every bit helps. Desktop apps exist. OSMAnd has editing built in.