We recently took a WestJet flight to Canada and the only way to access the IFE was via their mobile app - there was nothing in the way of ‘back of seat’ IFE as the hardware simply wasn’t installed. Perhaps Air France are beginning to take a similar approach? If so, it is essential to download the app before you get on the aircraft - otherwise you have to buy Wi-fi access on the aircraft, then download the app, then use the free IFE app which you have just paid to get Wi-fi access to download!
So, in the absence of any other info I would definitely recommend you download their IFE app to your mobile and tablet of choice before getting on the aircraft. If you find the aircraft you eventually get on does have conventional hardware IFE you have lost nothing and can just delete the app after you return if you don’t want it.