While firefox doesn't really have an 'app' mode¹, it can sort of be emulated by using a separate profile and a custom userChrome.css for that profile that hides most of the chrome.
See https://askubuntu.com/a/487954/167099 for details.
What this doesn't provide, afaict, is a way to customize the window title and icon (the shell will keep associating this new window to firefox instead of considering it a separate app).
While firefox doesn't really have an 'app' mode¹, it can sort of be emulated by using a separate profile and a custom userChrome.css for that profile that hides most of the chrome. /askubuntu. com/a/487954/ 167099 for details.
See https:/
What this doesn't provide, afaict, is a way to customize the window title and icon (the shell will keep associating this new window to firefox instead of considering it a separate app).
¹ https:/ /bugzilla. mozilla. org/show_ bug.cgi? id=1283670