Surfingkeys browser extension has a similar functionality to edit text area. Ctrl+i will open a in browser popup with an emulated vim editor and on saving and closing it with :wq the text area is updated with the new content.
Edit: So I tried it myself, disabled Surfingkeys and installed Tridactyl. To use the editor functionality, something else called nativeinstall needs to be installed. Instead following the instructions by executing the command that downloads from git, I installed the Tridactyl and the nativeinstall from the AUR: yay firefox-tridactyl firefox-tridactyl-native . And it truly opens a new window outside of Firefox, managed by my operating. But its the stock settings for Gvim and does not pick up my Neovim setting. I wish there was a way to tell it to use my terminal window with Neovim instead.
Edit 2: I figured it out. Download and put the default configuration file from github.com/tridactyl/tridactyl/…/.tridactylrc to ~/.config/tridactyl/tridactylrc . Uncomment the following line
then change the part “st vim” to something you want to use. In my case to “konsole -e nvim” . Then restart Firefox or do a :source in the browser to make use of the new configuration. In my case this seems to work and is loading my current Neovim configuration. Tested it with this reply. :wq