As a prior child who now has nearly 30 years of IT experience, that’s adorable. 10 minutes of research and you have been defeated.

Anything parents do just slows down a determined child. You can build a faraday cage for the pc, airgap it, install an obscure operating system that doesn’t know what a network or a flash drive is… and they are just going to go over to their friend’s house to use theirs.

Just be a decent parent, and for gods sake don’t be overbearing. That’s all you need.