If you want me to shorten things in the future I can by the way, but I'd have to be less detailed.
Vegan-wise as long as the animal consents, which means harvesting shit in the forest that was abandoned there, or buying or using another persons is fine, vegan-wise.
Yes, it originally (maybe?) came from poo/digestion, but it thrives in the dirt on it's own now.
Still like I said it's a non-issue.