This is a much needed and underrated feature and wouldn't be hard to implement at all. This should be prioritized for the benefits it offers especially with how easy it would be to integrate it.
Someone please get on this quickly! it wouldn't take too much time also!
Any recommendations for how this full screen user experience should work? Any examples of other apps that implement full screen well? Would you like a button to make the browser full screen?
Or should Firefox automatically hide the system toolbar when you scroll, like how it hides the address bar when you scroll? I see that Firefox, Chrome, and Safari don't hide the system toolbar when scrolling on a tablet, but I see Firefox, Chrome, and Safari on an iPhone (but not on Android phones) do hide the system toolbar when scrolling in landscape orientation. I wonder why not on iPad.
Would you expect the same behavior in both portrait and landscape orientation? Should Firefox on phones or foldable screens have the same behavior?
There is a risk that malicious web pages might mimic the system status bar without needing to trick the user into clicking Firefox's full screen prompt.
We would need to make sure that users could escape the "system status bar is hidden" mode if a web page prevents the user from scrolling (maliciously or otherwise). That might be way Safari and Samsung Internet only hide the system status bar in landscape orientation.