“Many countries don’t have industrial animal agriculture.”
Even if some farms are small, the overall system is still industrial. Milk, meat, and eggs are processed, packaged, and distributed through large corporations. Small farms still rely on industrial slaughterhouses and transport. Small farms don’t erase the ethical issues either. The same harms still occur like forced breeding, calf separation, slaughter of male calves, and early death of cows.
“there aren't any non-petroleum based fabrics that practically work well in cold (below 0 °C) climates”
Most people already wear synthetic winter gear, not wool.
“Are you telling me that one can run an organic farm, without any animal husbandry (including bee keeping, introduction of pest control animals, etc)? No industrial fertilizers, pesticides, weedicides, etc? Could you give me an example of this type of farming practice and how successful it is?“
You can. It's called veganic farming. You use compost, green manure, crop rotation, mulching, and nitrogen fixing plants. Animals aren’t required to grow food.
“Wouldn't supporting local small scale and free-range systems be the best option?“
No. Animal farming including small farms require more land, water, crops, transport and more emissions. Feeding plants to animals and then eating the animals is always less efficient than eating plants directly.
“Veganism in India? Do you mean "Brahminical" vegetarianism (which is a can of worms, in itself)?“
No. Veganism is not tied to cast, not tied to religion, not tied to purity rules. It’s simply avoiding animal exploitation.
“animals need to be bred and killed, but not unnecessarily. Since you brought up "ancient systems", you must also be aware of how ancient systems respect and care for animals, their deaths are revered and every part of an animal is used.“
They only “need” to be killed if we decide to keep using them. If we stop using them, the “need” disappears, even if ancient cultures treated animals with more ritual respect, animals were still bred, controlled and killed. “Respectful slaughter” is still slaughter. Ancient practices don’t automatically justify modern choices. Tradition doesn’t override ethics.