In my opinion, if you were able to put social networks in the sidebar as a work, you could get a lot of audiences, because in any case firefox is already very comfortable and with this implementation it would become truly perfect
if you set "full-screen-api.ignore-widgets" to "true" the fullscreen will be contained inside a window (at least on linux) but you lose the ability to go into a "normal" fullscreen mode.
Sidebar in the left corner with quick access to social networks.
I think Firefox needs to add a sidebar with quick access to social networks (Facebook, Instagram, Twitter, Messenger, Whatsapp, etc), as well as the ability to add your own favorites.
In addition, the possibility of putting or removing the sidebar, as well as putting the history button, downloads, etc. in the sidebar.