Many parent control apps are more like Spyware and are often also exactly that, Spyware which spy on your Kids. Or Google Family Link is also a great example which you can’t remove even if you want too (as parent). I already setup a non-child-friendly blocking DNS and set the Age Limit in the Google Play Store and did all the Privacy related stuff, but I’m still thinking how can I make a Android phone more secure for children? The threads I’m talking about are non-child-friendly content, malware, scams, etc.
Thank you. By searching for a perfectly technical solution, parents could lose track of additionally classical parenting like good communications with their children from an early age, friendly interest in their online activities and teaching them that there is sometimes disturbing content online, but you are always there for them to talk without judgement. Anyway I would suggest a few technical solutions like (already mentioned) routers DNS filter and default search engines suitable for children.