Fantastic! I always wanted this! Great work!

If it works in Private mode, I would rate 5/5.

Brilliant. Works as expected.

Firefox is still opening files with wrong programs after installing this plugin. For example opening PDFs with Krita or GIMP instead of Okular. I just wanted Firefox to open files as configured in KDE-Plasma. I can manually configure Firefox to use the desired programs for each MIME time but there are several of them, and it does not even show Okular as an option so I have to manually introduce the executable path which in most cases changes between verions (IE a folder with the version number).

Total problem solving extension! Using along with GSconnect to get total control of the computer using phone. Great extension!

It also works great with KDE connect so you can control firefox visiting media sites such as youtube from your phone. Kudos