Hahahah oh man my thought of what funny stuff those sorts might lead to mostly centered around kids at school getting in trouble, but this is way, way better. :)
On the darker side of things I was also concerned about people in abusive situations with hidden phones getting outed, which probably also happened. :(
(I am not a bright guy so I can't take credit for coming up with that on my own, I saw someone post about it on Mastodon.)
By that thought process, wouldn't these people more likely to have their hidden phone discovered by spontaneous Amber Alerts? Those come with no warning, whereas the NAS did come with a heads up.
It's not relevant to me, i'm in a different country, but in i've seen daily completely turn off your hidden phones, and only turn them on when it is safe because the alert will still blare when you turn on you phone the entire week before the test and also months before. Certain circles take warning each other about 'Loud Day' seriously.