So it’s made of shit, right? And shit is an animal product. But barring a night of drinking or a particularly aggressive burrito, shitting does not harm the shitter; it’s beneficial and required. Also the animals in question can and do consent, does that make it vegan?
It’s a bit tenuous to me to say that it’s “made of shit”. Made from shit yes, but it’s no longer shit at that point. It’s made from atoms that were originally part of molecules that comprised shit.
Fertilizer is often (most often?) made from shit. Would you say the plants that grow from shit are “made of shit”?
Modern fertilizer is generally made through chemical processes. It’s why we don’t harvest guano islands anymore. Nowadays they use the haber bosch process to make ammonia from atmospheric nitrogen.