Hello,
I just noticed this (apparently as of yet experimental) implementation:
Yes please! And I’d love to see that menu all the time, not only after the initial highlighting with the familiar methods. That would be great. That’s all, keep up the good work! This just got me excited for some reason.
This is indeed an experimental feature but one of Catalina 
Unfortunately there’s no API or documentation so that we can’t complete & fix this.
Huh, that really seems to be a running theme with apple’s documentation. Either I just don’t get it most of the times or it is just as notoriously bad as I usually claim it to be - at least as far as macOS/ Cocoa stuff is concerned. I’m snooping around PDFKit right now, PDFAnnotationUtilities.h isn’t well documented. PDFAnnotationSubtypePopup? I don’t even.
Anyways, I’m looking forward to a working version of the feature 