[kawogi]

LineageOS was just the easiest for me personally (was already installed anyway). But aren't there parental tools to lock down phones for non-tech people?

Another middle ground would be to insert no SIM card (my kids only had access via WiFi at first) or to disable mobile data.

Maybe my kids are special, but so far it was enough agree upon rules about what they are allowed to do. As soon as they break the rules they will loose some of their benefits. No rule works for everyone, but simple "no" to a technology that has so many upsides for our family life is also nothing for me.

Edit: also "selling a locked-down phone" is exactly NOT a solution. Parents will have to learn the up and downs of this technology and apply an individual solution to their situation.