It would be great to be able to match the built in PDF editing tools that Microsoft Edge has, specifically the highlighting and drawing tools. This is one of the reasons I can't use Firefox for working with PDFs.
Jumping in this thread with some exciting updates that are coming soon to the PDF editing functionality in Firefox. The team is working on supporting highlighting and commenting as well as adding images to PDFs. See the following threads for more info:
I hope pressure sensitivity for the Draw tool is part of the upcoming improvements. I'm back in school after a few years away; back then, I was a Windows user and found Edge pretty good for drawing on PDFs. I was disappointed to see Firefox doesn't support pressure sensitivity, highlighting, nor comments.