Obviously, I know its impossible to completely child-proof a PC, but theoretically, what steps would you take? Assume its a laptop with internet access, meaning you’d want local solutions and something like a pi-hole wouldn’t work well.
I would personally assume, you’d want to:
A) discourage internet exploration by offering ready-to-use options for most needs, such as thumbnails/bookmarks for common websites.
B) Implement some sort of blacklist for common or easy-to-stumble-upon negative content. Maybe something as simple as a Ublock filter?
C) Robust monitoring tools, although I have no idea what.
Edit: To be clear, I know education is the number one tool, but let’s say a tech illiterate friend is asking for help. What might you set up for them, or recommend they use - tools to assist in parenting, not replace it.
If you are going the Windows route Microsofts family settings can create a child account that is locked down and has usage time limits and a bed time that will lock the PC.
It isn’t perfect but does give you some insight into what they are using he PC for.
Google do something similar for Android devices + Chrome/Google search.
OpenDNS has a family friendly DNS that is filtered and free to add another layer to any device.
As others have said anything you do will only slow them down. It’s like swearing, you can ban them doing it around you but they’ll still do it at school with their friends. Sometimes they’ll slip up and use a word at the wrong time and you will have to remind them what is appropriate but as a parent it’s what you are there for, helping them form a decent set of guidelines on what and when things are appropriate.