> It is difficult to square the notional unconstitutionality of this with the fact that the exercise of other Constitutional rights have long been conditional on age.

Some of this depends on whether the state has an interest in preventing known, broad harms - say in the case limiting minors ability to consume alcohol.

Conversely, there are no clearly proven, known targeted harms with respect of youth access to app stores (or even social media). What there are, are poorly represented / interpreted studies and a lot of media that is amplifying confused voices concerning these things.