It's interesting that when Dale Vince (owner of Ecotricity and vegan evangelist) bought Forest Green Rovers a few years ago, he insisted that only vegan food was served in the ground and for player's training. It caused a huge kerfuffle at the time, but the team has been going from strength to strength.
https://www.fgr.co.uk/visit-us/matchday-food-and-drink I wish he'd buy the catering at Villa Park, it looks light years ahead of ours.