Either you haven't heard of or used Gnome Maps (which is wonderful, highly recommend), or it doesn't fit your criteria. Assuming the latter, what do you consider missing?
Gnome Maps is not even remotely competitive for offline use. It requires internet lookups for everything. Because OSMAnd maintains its own OSM database on your device, looking up opening hours for businesses can be done with no internet access.
OSMAnd is able to show all kinds of details about roads (such as the road surface – important for cyclists interested in asphalt/unpaved riding).
Gnome Maps also uses GraphHopper for routing. OSMAnd, on the other hand, allows you to extend its routing with plugins, so long-distance cyclists can install the Brouter routing engine that is superior for this kind of travel.
Either you haven't heard of or used Gnome Maps (which is wonderful, highly recommend), or it doesn't fit your criteria. Assuming the latter, what do you consider missing?