What I'd like to be able to do is unify the tags between Firefox and my Emacs org-roam/org-mode data. I think it could be useful to be able to see a view of which bookmarks have the same tags as the document I'm viewing, and vice-versa. Plus a timeline of tags/bookmarks/documents/pages could further bring to light some relationships between information. For instance, "around the time I was writing lots of stuff about AWS IAM roles, I bookmarked these pages, read these sites, browsed these tags".
It's only a half-formed idea and unfortunately it'd require both lots of Emacs elisp work and an extension in Firefox.