Thanks for the replies!
I actually went to Reckless right around the corner from Dusty Groove when I was in Chicago a while back, if only I had known about it then.
To give some recommendations myself:
Red Light Records in Amsterdam always has a good amount of library LPs. The stock (of the entire shop) is small and expensive, but very well curated. This is (one of) The Alchemists favourite record shops.
Platypus recordshop in Amsterdam is new so I haven't been yet, but judging by their Instagram they seem to have a selection of library records among other rare stuff as well.
Sadly there is no (partly) dedicated to library shop in Amsterdam, although Redlight comes close in being dedicated to well curated rare/unusual stuff.
I dream of one day walking into an Amoeba sized shop filled with library and japanese records, with an unlimited budget in my pockets lol. One day