Setting a BIOS/UEFI password might help (But doesn’t always). If that does not work on your computer, you could try replacing the windows bootloader with grub as the default bootloader in a weird windows menu. (I don’t remember exactly how I did it. You should search for something like that on the internet.)

I’ve seen it on several phones in the EU, but I don’t know about NA.

On some devices windows puts itself first in the boot order. I’ve seen this on some HP devices.