A few tweaks are required to make vegan dwarves completely practical in Dwarf Fortress. This mod adds cloth quivers and backpacks, which can be made at a Craftsdwarf's Workshop, using the Clothesmaking skill.
I'd also recommend turning off artifacts (strange moods), which often demand bone or other animal products.
To do this challenge properly, you should never use any kind of animal product. That includes no wool, no silk, and no beekeeping. Keeping pets is fine, but training or using war dogs (or other war animals) would be unethical.
Here's a list of labors you should disable:
- Hunting
- Trapping
- Small Animal Dissection
- Butchery
- Tanning
- Cheese Making
- Milking
- Shearing
- Beekeeping
- Gelding
- Fishing
- Fish Cleaning
- Fish Dissection
- Leatherworking
- Bone Carving
- Wax Working