how would this actually work? iOS is so dominant among US teens it's crazy, and the ability to sideload on that platform is nonexistent even to very technically savvy users.
I'm not saying it's more likely that not, but I am saying I wouldn't be surprised. If you replace "one specific social media app" with "iMessage", it has already happened.
I don’t think the average American high school student has two smart phones one of which is a secret from their major source of income (their parents).
There's no use for a cellphone plan, we would just use wifi or hotspot from their main phone.