/usr/include/osmium/geom/ is in libosmium2-dev 2.11.4-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/osmium/geom/coordinates.hpp
/usr/include/osmium/geom/factory.hpp
/usr/include/osmium/geom/geojson.hpp
/usr/include/osmium/geom/geos.hpp
/usr/include/osmium/geom/haversine.hpp
/usr/include/osmium/geom/mercator_projection.hpp
/usr/include/osmium/geom/ogr.hpp
/usr/include/osmium/geom/projection.hpp
/usr/include/osmium/geom/rapid_geojson.hpp
/usr/include/osmium/geom/relations.hpp
/usr/include/osmium/geom/tile.hpp
/usr/include/osmium/geom/util.hpp
/usr/include/osmium/geom/wkb.hpp
/usr/include/osmium/geom/wkt.hpp