I'm not sure collecting kids biometrics makes anything better. Fingerprints are easy to find, capture, and replicate using things students have readily available like glue or gummy bears (https://it.slashdot.org/story/10/10/28/0124242/aussie-kids-f...). Once a fingerprint is compromised the user is screwed forever because it can't be reset.
You have a point, but I don't think a thirteen year old slashdot post is the best way to illustrate it. Fingerprint authentication has to be implemented correctly, or else it does face the problem you mentioned, and other ones as well. Which Apple did. You can't steal the fingerprint out of an Apple Secure Enclave and compromise it like you're thinking. So it would need to be done right, which Google is capable of mandating for Chromebooks.
As far as Gummy bears are involved, my read of the Cisco Talos Threat Intelligence group report*, vs the competency and resources available to 13-year olds (who are not to be underestimated, tbc), is that the gummy bear trick no longer works.
