I have one of those at home. The idea is to stuff a Pi in it and use it as the terminal access for my local "NAS" (two hard drives connected to the Pi).
One of our local entrepreneurs, Xavier Niel, first made its fortune by selling pornographic services through Minitel.
Cool! My dad worked on this in the 80s. Like the web but much more centralized. Not that the web is decentralized much these days though...