Over at Wikipedia, the Navigation popups instructions for "Installation on remote MediaWiki installations, or via your global.js" provide instructions only on loading for a single user. How can one load it for all users? Placing the recommended js in the remote wiki's "MediaWiki:Gadget-popups.js" has no effect. That recommended js is:
// [[Wikipedia:Tools/Navigation popups]]
mw.loader.load('https://en.wikipedia.org/w/load.php?modules=ext.gadget.Navigation_popups');