This is really not that hard. Modern app culture is highly addictive and provably poison for our brains over time. Adults can choose poison if they wish but when they give it to their kids it is called child abuse.

With my kids, I oversee everything they do (they are under 6). They average 15min daily for two episodes of a kids show.

I'm not saying go to zero. But definitely not over 3 hours and definitely not a dedicated device for them.

Regarding my kids: high priority, wide/curated choice (not in terms of restriction, but in terms of actively finding things they may like), accompanied learning, and, crucially, starting from a very young age. It's pretty much standard parenting, that is, one gets out what one puts in.

By the time children start to pressure for this type of devices (say, 10/12), they will have learned to enjoy books and more creative activities.

The group of parents who let their kids smoke might get those instead, improving their health

The parents who don't allow it would never consider them

I suppose it depends how many of group 2 could be converted to 1 if they were "low tar!".. my intuition is close to zero