You might like the "Custom Buttons Bookmarklet Maker" I use it to have a button ...

You might like the "Custom Buttons Bookmarklet Maker" I use it to have a button for adding videos from a page to my Plex queue, removes the need to have the bookmark bar on screen. I found it rather arcane to set up however.

https://addons.mozilla.org/en-US/firefox/addon/custom-button... ... ah, and now I see it's unmaintained and recent version isn't working for some, carry on, never mind (works for me though).