What is your motivation for the "without a sim card" part? If the phone is connected to Wifi then they're either at home or at school--isn't the point being able to reach them no matter where they are?
I'm not too keen on my kids being on the internet all day. In my case the opposite solution seems better, a dumbphone so I can reach them, but TikTok can't.
Shared custody? I like being able to communicate, send/receive pictures/videos, do videocalls with my daughters when they are in their mother's place without having to ask her to share her phone for that.
I am actually travelling 10 thousands kilometers away from them for a month, having an instant messaging app is a saver for both me and my daughters.
We are currently using deltachat for this with email accounts I set up for them. They don't even have access to these accounts outside of deltachat yet and they can't be reached by others like they would with whatsapp.
They're mainly not online, and not signed up to online services, but it'd still be nice to be able to message the rest of the family, listen to music, share photos, etc.
