Most studies I've seen show "long covid" to be pretty rare in children. Perhaps something like 5% of children who test positive have mild symptoms a month later. [1] This is somewhat consistent with other respiratory virus infections we've known about. [2] It's possible our risk tolerance is way different but this is personally an acceptable number for me not to worry about my own child.
[1] https://www.cidrap.umn.edu/news-perspective/2021/08/long-cov...
[2] https://pubmed.ncbi.nlm.nih.gov/31718695/