Its a great idea and I will buy a few for sure. Thanks for pointing it out.
I developed a vegan cryptocurrency a couple of years ago called Voin. Unfortunately I never persuaded anyone to use it. However it was a good learning process.
Cryptocurrencies work best when the blockchain is small. Mining is easy and transactions are fast. For this reason niche coins make sense.
Veganism is not the ideal niche. Most vegans are women who don't tend to be interested in cryptos and nerds aren't interested in health or animal rights. One comment on bitcointalk on my coin was that if it had been called bacon coin he might have bought it. This is the attitude of most people in this space unfortunately.
The other challenge is how to make it vegan. How do you stop people using it to buy non-vegan products.
Over time these problems can be overcome no doubt, and a vegan cryptocurrency will play a big role in creating a vegan world.
I am vegan and also heavily invested in crypto.. Also there could be rewards for buying vegan products.