Yeah you can get B12 vitamine from fortified foods such as plant based milks and cereals. Also it's recommended to take B12 supplements anyway even if you are eating a lot of fortified foods. It's 100% safe because it’s not a fat soluble vitamin. It’s water soluble so you cannot possibly overdose on it.
I read if the fortified foods use isolated iron this will cause overgrowth of gut pathogens. You can overdose on iron, it is a very complicated system regarding iron uptake between the gut and our gut bacteria. The doctors are finding iron supplements thought to protect from malaria actually harm the host and make infections deadly.