I’m buying KF94 masks for Kiddo. Check out Aaron Collins’ mask test/review video and data spreadsheet for kid masks:
Kiddo (12) likes the Bluna mask with the duck on the package (adjustable ear loop) and the Happy Life mask with the puppy on the package (ear loop not adjustable). BOTN masks come in different sizes; the medium fits Kiddo ok, but she has to double up the ear loops.