(The issue of "primary owner of the device" being the most problematic.)
Equally the concept of "app store" is different for different OS's. iOS and Android are clear. Mac and Windows are mostly "download and run from website" (although both want to pivot to appstore, with varying degrees of success.)
Then we need to wonder if yum and apt are stores, given that they aren't actually owned by "linux".
In truth though it kinda doesn't matter. It's trivial to add an "age" field to account creation. It's trivial for users to enter any date they like. So on the one hand it's easy for OS makers to comply, it's easy for users to lie.
Presumably if the law could have mandated age checks then would have, so I'm not even sure thus is slippery slope. Most minors don't have photo ID. Most desktop hardware doesn't have a camera (at the time of account creation.)
This feels like performative law-making. Vague language. Unenforceable user participation.