I have an existing tool for adding links from OpenStreetMap to Wikidata.
We want to add links in the other direction, from Wikidata to OSM.
Wikidata now has properties for OSM relation, way and node ID.
(property is two months old)
732 natural=cliff
486 healthcare=hospital
428 amenity=drinking_water
168 building=chapel
162 booth=K6
143 amenity=townhall
129 amenity=cafe
126 amenity=college
123 building=house
97 shop=mall
80 natural=strait
73 man_made=water_tower
72 tourism=zoo
69 tourism=gallery
66 historic=wreck
62 amenity=public_bookcase
62 amenity=bar
58 military=airfield
54 amenity=community_centre
44 craft=winery
41 barrier=toll_booth