Which operating system is best for a child-friendly gaming PC?

I’d choose Windows unless the computer is going to be used almost exclusively for gaming through a simple launcher. Windows is the dominant consumer platform, so you’ll generally find more compatible games, parental-control utilities, and documentation for setting up restrictions.

The nephew’s age and what he’ll actually do on the machine matter too. If he’s very young, account restrictions, filtered DNS, supervised browsing, and clear time limits may be more important than the operating system itself. For the least hassle, Windows is still the straightforward recommendation.

Windows is the better fit here. It has much broader support for built-in family features and third-party parental-control software, along with easier tools for managing accounts, apps, websites, and screen time. Linux can be configured with separate user permissions and filtering tools, but it usually takes more technical effort and doesn’t offer the same polished selection of child-safety options.

Linux can work if you’re comfortable managing it yourself. You can create a limited user account and use network-level DNS filtering or other blocking tools to restrict adult content, gambling, social media, and ads. Just be aware that this is more of a DIY setup and may require ongoing maintenance.