MediaWiki Action API is organized in categories: query, page, list, and meta. for instance recentchanges. For instance: https://pzwiki.wdka.nl/mw-mediadesign/api.php?action=query&list=recentchanges click on add json, indeed adds json. Looking at the docs, seems like we can add user to the default value of rcprop (title|timestamp|ids) to see the user.

CORS is indeed the default mode of fetch accordings to the docs. But it needs to be enabled on the xpub wiki!. Actually in the end, I just needed to add origin=* to the request (weird).