I’m not vegan but use products from TRIBE (https://wearetribe.co) which are vegan. Their Choc Salt Caramel Infinity bar tastes awesome and is great for endurance rides (25c, 8f, 7p). They do protein shakes and all sorts, highly recommended.
I also use bananas, dates when out on the bike or on the trainer. Maybe some toast and marmalade before a hard session.