Why not just (a) make it illegal so the parents and tech companies see it that way and (b) put some fines on the responsible adult parties if violations are found?
Sure enforcement would be spotty and loose, but tickets for parents and fines for tech companies would go a long way to establish the cultural change without the need for "verification"
A company can't work like that - the tech company will need to do it's upmost to avoid the fines, and so will implement verification that is both unsafe, incredibly invasive, discriminatory but crucially has an audit trail, and it's insane to suggest they would do anything else.
If companies are motivated and parents are motivated to prevent it and schools have the cover to also police it, then social media usage probably won't hit critical mass for kids and they won't feel FOMO to get it.
"it's illegal" is usually a decent enough hard stop to most kids for "why can't I have it"
Should just age-restrict smartphones altogether imo lol. Entire generations survived without mobile phones and it would remove entire issues around addictive mobile games, social media abuse, attention/focus issues
and you'ld learn how to code just like millions have for decades - in school or library computer rooms, or with an age-restricted computer that your family would provide.