I consider creatine and O3s a bio-hack more than a supplementation.
B12: yes. But most meat people eat has been fed a B12 supplement as well (as live stock do not live on dark soil that is abundant in B12; they live on concrete floors and eat factory-produced animal feed... with B12 added to it).
Calcium: nope. Magnesium is more important IMHO; IFF you do not get 2 portions of low-oxelate (most are low-oxelate) leaves per day. I try to get the leaves.
Iron: mostly a thing for menstruating women.
Zink: mostly a thing for ejaculating men.
As a vegan (for moral reasons) I take D3, B12, some Magnesium and sometimes Zink as supplements. I do bio hack myself: creatine, high DHA O3s, but also recreational/experimental drugs.
I agree veganism makes it harder. But I dont think that's what veganism is about: it is an ethical stance. If you are "eating a vegan-compatible diet, but not vegan" we should use another word: plant based diet (which includes fungi, yes, weird).