Veganism is the idea generally that humans should do their best to live without animal products. Some may ideologically believe animals deserve complete autonomy and separation from humans, while some may believe that in the society we currently live in, there is no ethical way to consume animal products because modern factory farming is egregiously brutal. In the United States, animals are sadistically tortured in the name of science or animal products. They are cut open, have parts amputated while alive, or are force fed to the point they are obese and their legs break. Many comrades would agree that animals are an exploited form of life, even if they cannot be called a class since they are unable to articulate their experiences or a class identity.
One of the largest issues with veganism is the extremist mentalities of some participants on the internet. There are stories of vegans being put into positions where they have nothing to eat but eggs, such as in a hospital setting. They receive death threats or harassment, which is more likely to make them leave the lifestyle. It also seems to reflect neoliberal ideas where everything is blamed on the individual regardless of material conditions that caused them to go against their diet such as lack of availability or economic reasons out of their control. In the third world where people do not have the privilege to always choose vegan or vegetarian meals, they need to eat meat to meet their food requirements. This is rejected by vegans in the first world and a person would be demonized by some people for not having a completely pure diet, making them less likely to become vegan and continue down the path of reducing animal harm.
As an Ecomaoist, I do not personally believe that humans and animals must be segregated and exist completely independently of each other. Animals such as sheep or cows are actually good for the environment, make good companions, neighbors, and can be shepherded around to maintain the environment through their grazing and manure patterns. Secondary products such as their milk or their fur could also be harvested humanely in such a situation, which would fix the ethical dilemma associated with such products. Modern factory farming is not only wrong for the torture animals are put through, but the animals in factories are not able to help improve their local environment through grazing and spreading of manure. This contributes to desertification and the loss of minerals from the environment over time. In a situation where animal cruelty is not a problem, a vegan lifestyle can still be beneficial for the planet and efficiency of the world’s resources for feeding the population.
Adding onto this, the only reason an abundance of "secondary" products exists is because we disgustingly bred animals like chickens to produce more eggs than is healthy for them which frequently leads to vitamin deficiencies and genital issues that cause death.
Sheep need to be sheared only because they were bred to have such thick coats that they may even overheat to death without the wool being trimmed.
There is no ethical way to obtain these products now because they are inherently a product of exploitation, and if animals went back to their pre-human bred states, there wouldn't be then either because they would only produce as much as was needed for their own benefit or the benefit of their offspring.