There’s a script(or I think technically rule) you have to paste in and it works, on phone so dont have it on me rn

Was on Google cause I just initially was setting them up there. Moved to cloudflare the day they added dev tlds.

FF has tab containers which, while I haven’t used much myself, seem pretty similar to tab groups from a quick search. Edit: Also looks like there’s “Simple tab groups” extension which maybe even more similar to what you may want