Hi Karl! Thank you for this question.
It would be fantastic if we had such specific guidelines for screen-use, and for each platform like in your example. Unfortunately, there isn’t enough data to even get all experts to agree that excessive screen use IS actually an issue at the moment.
When I speak to both clients and friends who have kids, I always advise no screens of any kind before the age of 2 for sure, but ideally 3. There just simply isn’t any need for them. The physical and psycho-emotional milestones children need to reach at that age require only one ‘device’- the parent. FaceTime with relatives and friends who are far away is perfectly fine though (as long as the child is kept a good distance away from the screen, due to ongoing eye development).
Past this age it gets a bit tricky, again, due to a lack of conclusive research. And this is where we can really empower parents because they know their children best - we can support and coach them through identifying the limits for their children. Some of the questions they can ask themselves are: are my kids really learning new and/or useful things, are my kids really strengthening relationships by using devices, are my kids strengthening their imagination muscle by using tech, is tech helping my kids develop their learning habits? We also need to help parents strengthen their ability to stay attuned to their children’s emotional signalling, so that they can tell if their child is becoming overwhelmed by tech, suffering from FOMO, and using tech to alleviate boredom, to name a few. To do this, we of course need to help parents learn to look up from their own devices more often too!
I second the comment about Dr. Livingstone - I follow her on social media and really love her measured but firm views. Recently, her and Dr. Jean Twenge exchanged some words on Twitter which I found quite interesting to observe! Another good person to follow is Dr. Victoria Dunkley who is quite outspoken about tech-detox for youth, and Dr. Jenny Radesky is another important figure for this issue from the American Academy of Pediatrics. I also like UK-based internetmatters.org as they have a good amount of research and practical advice.
Hope some of this is useful!