Just so Android users aren't wasting their time:
> Messenger Kids is currently available in the App Store for iPad, iPod touch and iPhone. We plan to launch the app on Android devices and Amazon Fire tablets soon. While a child currently must use Messenger Kids on an iOS device, parents and other approved adults can chat with the child from any device the adult uses to access Messenger.
I honestly feel like this petition misses the point of a parental controlled messaging app. From the page:
That'd be positive. Do you have any idea how they do the verification that it's only kids? I'm guessing it'd be similar to how Messenger for Kids work - do you know how?
Edit: I guess there's no verification, just parental controls on who is added https://messengerkids.com/how-it-works/
I assume that works as long as you only let your kids add kids they know in real life.
Facebook has Messenger for Kids. Parents set it up under their account and kids cannot friend anyone nor browse FB since they don't have a FB account. It is crossplatform.