You can't get to 0
And I mean everyone in the world unless we a) close the borders completely for absolutely everything, or b) implement covid passports.
There's no data about prevalence of long-term symptoms after an infection yet, regardless of whether people show immediate symptoms.
There's also no data about the prevalence of long-term symptoms of the covid vaccines, since it's literally impossible to test the 2-5 year effects of something that's only existed for one year, so by your logic should non-at-risk populations avoid taking that?
It's a complicated situation, and there's likely no perfect answer. However, it's definitely not as black-and-white as "if they don't get sick, they don't get sick", and such reductionist statements don't help make an informed decision.
If kids don't get sick, then they don't get sick. What's foolish or difficult to understand about this? BTW when someone says "kids don't get sick from it" they don't talk in absolute terms. Kids also can get cancer, yet we are not screening their prostate yearly like we do with old men.
Wanting to harm children's future, education, development and mental health because out of your own fear is rather distasteful.