Current law does not punish those who are under 18 who participate in porn or streak at their high school football games (except to the extent they get fined for public indecency), and there would be no legal justification for punishing older teens who do so, either, in the unlikely event the age limit for participating in porn were raised.
Teens prosecuted for racy photos...
Teen girl charged with posting nude pictures on the internet...
etc...
In the first case, it should be noted that there wasn't even any distribution of the photos involved. They just existed.