Appropriate screen time for children, how much is too much?

This is hard to answer as it can vary depending on the age of the child, the type of activities they are engaged in, and their individual needs.

The Australian Government's Department of Health has published specific recommendations for age-appropriate screen time limits for children. Children aged 5 or under should have no more than 1 hour of educational/entertainment screen time per day, with no screen time recommended for children aged 2 or under, with the exception of video calling. For children aged 6-13, no more than 2 hours of educational/entertainment screen time per day is recommended. In addiction to any screen homework.
Internationally, the Canadian Pediatric Society recommends limiting screen time to no more than 1-2 hours per day for children of school age, while the American Academy of Pediatrics recommends limiting screen time to no more than 1-2 hours per day for children 2 to 5 years old.