Ask HN: What is your policy regarding smartphones for your children?

Recently, there are more and more studies that smartphones harm learning and not a single study with the opposite results. However, very few parents have the guts not to buy a smartphone for their child. At what age do children in the HN crowd begin to have censored access to proprietary software (personal supervision) and uncensored (smartphone with or without parental controls)? Are there families where children have access to computers with only FOSS before they have access to proprietary software?