JetOS is an operating system powered by Scratch. It is not bootable, so don't even try it. JetOS is made by FarAhead Systems, a member of the Scratch Computing Alliance
All JetOS versions not labeled under "Scratch Versions" do NOT work in Scratch. They may boot, but it will be broken.
Versions: Donut Milestone 1, Donut Milestone 2, Donut Milestone 3, Donut 1.0, Donut 1.0.1, Snowcone Technical Test, Snowcone Technical Preview, and all older versions on Scratch use fonts exclusive to Windows. I can't assure that it will look as intended on non-Windows machines. Newer versions don't have this problem.
JetOS was designed on a 1920x1080 laptop at 150% Windows scale. You may want to change your settings to that if JetOS doesn't look right