Absolutely not. For protein you need like... beans. It's not that difficult. It's fine for kids, and you absolutely don't need supplements. Vegan, maybe you do, not vegetarian.

Half of India is vegetarian. You think they're all sucking down pills and having short kids?

Everything you just said is wrong. Name these mystery nutrients. The only supplements vegans take are B-12 and D.

Vegans have better B-12 levels than the general population, who are significantly deficient, despite all the meat they shove down their throats. Everyone should be taking B-12 supplements. That's how it gets into the meat in the first place. Livestock don't produce B-12 either! Just grow up and take the pill instead of wrapping it in the flesh of an intelligent creature that at one time had the capacity to love you before you murdered it.

Have you ever bothered to check your D level? Most people who require D supplements are not vegans!

Along with your claims about children and North Korea (for some reason) it's clear that you're not talking from any kind of informed position, but you're just saying things that give you a psychological reward for saying them. It's a defense mechanism. This sort of behaviour is predicted by the theory of carnism.

https://www.bbc.com/future/article/20220525-is-a-vegan-diet-healthy-for-kids