While I was working with PP, I thought if we have something like " Network of comments" feature would be helpful for researchers.
This feature might work as follow:
You are reading a pdf then you comment or highlight something you think is interested. Also, you think you read something before that is connected to this specific new comment. All you have to do is to drag the related previous comment to the new comment. It might work for highlights too, you can link highlights between documents or pdfs within PP. This way you can build a network of connected ideas across your readings which would help a lot in your writing. You might also connect comments or highlights with URLs or Youtube links from outside PP by dragging them to the targeted comment or highlight. I just draw a pic to illustrate the outcome to make it clearly understood as English is not my first language,
I hope you get it,