But there are many other minimal UI browsers as well as Firefox that support no tabs.
I’ve been using qutebrowser which doesn’t have much of a UI since it is vim based
I'm using Firefox with a custom userChrome.css:
#TabsToolbar { visibility: collapse !important; }
Works quite ok but I cannot disable opening tabs completely in Firefox.
But there are many other minimal UI browsers as well as Firefox that support no tabs.
I’ve been using qutebrowser which doesn’t have much of a UI since it is vim based