Visual elements: https://osmand.net/help-online/license/

And fdroid shows it:

There is a topography plugin, you have to pay for it, but it’s free in the fdroid version: https://osmand.net/docs/user/plugins/topography/

There is also a topo map style, similar to OpenTopoMap, but no contourlines: https://osmand.net/docs/user/map/vector-maps/#topo

Mapy is another osm based map app (except for Czechia, map data is different there), some of my hiking friends love it, it’s not foss at all: https://play.google.com/store/apps/details?id=cz.seznam.mapy

Osmand is not fully foss as well.