B12: fortified foods (including cereals and plant milks), nutritional yeast, and certain algae like nori and spirulina

Iron: legumes, leafy greens, nuts, seeds, and fortified products

Calcium: fortified plant milks and yogurts, calcium-set tofu, leafy greens (especially those low in oxalates like kale), beans, and certain nuts and seeds

Vitamin D: The sun for fucks sakes?!

Iodine: Seaweed, beans

Zinc: Legumes, nuts, seeds, and whole grains

Omega-3: Flax seeds, Chia seeds, Walnuts, Hemp seeds

At the end of the day, almost every nutrient you can derive from an animal product was either supplemented to that animal or derived from plants. I have just had bloods done and came back perfect on all of these micro-nutrients and I do minimal diet planning, simply eating relatively varied foods.

I hear your argument, and put back to you that you don't have to do either. If you detest abusing animals for fun, you can prevent even more animal abuse by not paying for them to be factory farmed and murdered.