Probably a bit old fashioned now and a lot more complicated to make than you might think. phpBB relies on anything outside the 'shipped package' being made by people who want it and are happy to share it. If people don't really use them any more the chances of getting one made might be slim but you can ask in the extensions request forum.
Don't worry. Thankyou for looking in anyway.
Back when I started out in PHPBB Portals were the in thing. Kind of like a newspaper tabloid sort of thing.
Guess my age is showing and people just don't wanna bother with all that any more.