It IS possible for a cat to have a vegan diet as long as the essential nutrients are supplemented and you work with a vet. One big thing is taurine, but the way meat is processed in cat food removes the taurine so it is added back with synthetic taurine anyway.

You can read more about this in this thread:

https://lemmy.world/post/18691022

Also what is an obligate carnivore, does it mean they have to eat meat?

“Some carnivores, particularly cats (family Felidae), are obligate carnivores, meaning they cannot obtain all the nutrients that they need from the plant kingdom and bacteria. In particular, obligate carnivores lack the enzyme needed to split carotene, obtained from plants, into vitamin A. Instead, these animals obtain vitamin A from the liver of their prey. Obligate carnivores are similarly unable to synthesize some essential very-long-chain, highly unsaturated fatty acids that other animals can make from shorter fatty acids found in plant.”

So, an obligate carnivore is an animal that needs to (is obligated to) obtain some nutrients by eating the flesh of other animals (or those nutrients would have to be supplied in a form the cat can absorb by means of supplementation). Cats do not have the long digestive tracts of ruminants to efficiently ferment raw starch or fiber, but that doesn’t mean they cannot digest plant matter at all. It also does not mean they are unable to obtain any nutrients from plants or from fiber. However, being an obligate carnivore does mean that their diet MUST provide certain nutrients from the flesh of other animals or from supplementation.

https://rawfedandnerdy.com/what-is-an-obligate-carnivore

Studies on cats eating a vegan diet? Science says we need more studies because it is not as black and white as all the people kneejerking about it are saying.

Whilst the quality and amount of evidence needs to be considered in formulating recommendations, there was no overwhelming evidence of adverse effects arising from use of these diets and there was some evidence of benefits. It is, however, recommended that future high-quality studies, with standardized outcome measures and large sample sizes, be conducted. At the current time, if guardians wish to feed their companion animals vegan diets, a cautious approach should be taken using commercially produced diets which have been formulated considering the nutritional needs of the target species.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9860667/

I learned a lot by listening to the original commenters I linked above. Hope this helps.