Most people who don’t know their stuff uses nvidia. Happily slowly changing, but nvidia is everywhere, at least where I live. And people who don’t know stuff still hold onto “green good, red hot and bad”.
Every pre-built machine I have seen using Nvidia has it written on the front. Including the laptop I am using now. It works fine on Linux btw, provided you grab the right ISO.
Windows 11 installs itself automatically on newer machines as it did on my parents laptop, nags you if you refuse. Same way Windows 10 did when it came out. It comes with pretty much every new machine too. That’s what I mean by it’s the default. Windows 10 support also ends next year. You are severely out of the loop if you haven’t noticed, or you have an unsupported machine.
As for Windows breaking that’s what eventually made me switch to Linux again, Windows 11 taskbar decided to stop working on two different machines.
On Linux you need root permission to do much damage besides deleting files. You can create a non-root account for someone, or just tell them not do anything that prompts them for a password. There are few places where you can break something from a GUI in Linux, and those are things like disk managers that are equally dangerous on Windows. On Windows you can go to device manager and straight up disable devices. I’ve seen someone do that with their WiFi card. If it’s still an issue tell them to use Chrome OS or another immutable Linux. On those systems the OS partition is read only with snapshots in place. Those are almost impossible to fuck up short of reformatting your PC.