Ah there’s actually a wiki page with maps linked at the bottom amenity=public%20bookcase?uselang=en-GB

Hi, I was wondering the same thing recently. I’m relatively new with OpenStreetMaps, but Overpass Turbo was helpful for me in coming up with a map. It queries “amenity”=”public_bookcase” and shows them on the map

This link runs the query for San Francisco -> https://overpass-turbo.eu/s/1r9o You’ll have to click Run on the top left.

Let me know if you know of another way!