Creating links between PDF attachments

Things I have tried

  • Looked up plugins for this and there don’t seem to be any
  • Read up on linking, but there doesn’t seem to be a way to link between files other than typing [[]] in markdown. However, I am trying to link PDF files, so I cannot type [[]] inside them.

What I’m trying to do

I would like to create internal links between PDF attachments in my vault, so that in graph view there would be a connection between the nodes representing the PDF files.
I know that I can embed each PDF in a markdown file and then easily link the two markdown files. But I want the link to be between the PDF files themselves, not between some wrapper around the PDF files.