I have written a template called OSM Location map on en:wikipedia to put this template map into a frame, and do various other useful bits and pieces. At present it allows 10 markers to be shown, and is designed specifically for manual use, rather than the wikidata facilities you also provide. I am aware that there are probably parallel developments going on, which is fine if this gets supplanted, but it seemed like a good chance to find out how these maps might start being used. I have taken the chance to include a <maplink> link so that users can both see the static page map as optimised by an editor and link through to a more interactive one.
One strange bug I have come across is that when previewing a page under development, the labels all look very nice, with a fine-lined font, and with lots of colour options. But when changes are saved, all the labels become a clunky font instead, and most colours switch to black (or sometimes to the shape color. There are examples on the doc page for template:OSM Location map, or see . I get the same problem when calling the Graph: template direct - the labels - especially small font sizes - look far better in preview than for real.