You don’t need to search for Neffa Souffi - like with any other tobacco product, if it’s still placed on the market in France, simply ask any buraliste to order a carton of ten sachets (or other number; I’m not aware how many sachets of this Tunisian snuff are in one carton) for you. Although I’m not sure if it’s still sold in France these days. One thing is clear, it still was on the list a couple of years ago.
Up to (relatively) recently Sifaco’s Neffa Ifrikia was packaged in plastic tins, very similar to those which Pöschl packages their Neffa Bledi in. The photo of metal tin of Neffa Ifrikia which you have shared (thank you!) just a while ago is a new type of container for this nasal snuff product - it seems that Sifaco have started using same metal tins they package their chemma (Makla brand oral rustica products) in for their Neffa after the implementation of new Track & Trace system (bottom of the tin is marked with the new type unique tobacco product identifier code). Which is a good sign, i. e. Sifaco have not discontinued Neffa Ifrikia.