This is fighting a battle that doesn't need to be fought. Just get the hardware you want regardless of the OS that's pre-installed.
- You don't save significant money buying an "Ubuntu" laptop or whatever, but you severely limit your choices.
- Any pre-installed Windows OS will be full of crapware that you'll want to get rid of with a clean install anyway.
- It will be easier to resell later with the latest OS on it, if you ever want to sell it.