If you use matplotlib, you need at least 8MB of libraries and if you use cartopy, you needs also matplotlib, so the gramps package will grow aproximately 16MB for windows and mac users.
It’s difficult to add more libraries to gramps. the gramps package is already very big. (100MB for macs and 65MB for windows)
Linux is better managed for that.
matplotlib use its own maps.
cartopy can use some other maps (stamen, osm, google …), but I don’t know how to integrate it into the geography views with the osm-gps-map library. I needs to look at this.