Basically, teens can be tried for distribution of CSAM (Can't call ot CP anymore as Porn is a prefressiom) when they become adults if you follow letter of the law
They don't even need to wait for them to become adults. The cases I'm thinking of all involved minors who "produced child pornography" by taking said nude selfies, and "distributed" it by sending it to another minor. IIRC, there was even a case where a girl sent it to a boy she liked to try and get him to like her, and he shared it around school, and to add insult to injury, she was charged with a crime.
Looked it up.
But there are plenty of cases just in general, and the kid doesn't even have to be dumb enough to share the pics, they can just have them on their phone or computer. It's absurd, especially in the cases where they end up having to register as a sex offender and are barred from being around minors when they themselves are a minor, and now can't even go to school to finish getting a diploma.