Ubuntu used to send you a CD-ROM ready to use free of charge back in the day.

I’ve done this whole process hundreds of times and it’s straightforward now, but the first times where really confusing, I totally understand you.

you basically want to put the installer file in a USB, but you can’t simply copy and paste it because it needs to be “bootable”, that’s why you use a tool like Etcher or similar.

any link in the official Linux Mint page will point you to reputable sources so just pick the first one. the beauty of open source is that it’s not as centralized as a big corporation’s software, you have choices, confusing at first, I know, but it’s worth it once you get past the learning stage

In terms of keeping him safe online look into some content filtering for the whole home network, either paid or self-hosted.

Projects that act upon physical stuff are the most rewarding. Something simple such as building a simple Python script that interacts with a smart home API and turns switches on/off or changes light colors around the house are relatively simple and require no hardware/mechanics if you’re not into robotics, soldering or circuit boards.

You’ve got a great kid :)

Love Connect! It is the best, great work Kuro