The first time i really heard about fan tokens of football clubs was when the news came out last year that Messi will recieve part of his salary in fan tokens of Paris Saint Germain when he left FC Barcelona for PSG. I then searched a little and found out that there are many other clubs that are having official fan tokens already, but that it is pretty much all i know about them. To be honest i would be very careful to invest into such tokens. Like i said i did not really a deep research on them but as far as i know they don't really have a use case. You can pay for merchandise and other stuff from the specific clubs that you own the fan token from but that does not really give you any advantage over someone that uses FIAT to pay for those items.