A clean install of Windows 10 (not n versions) is shipped with stupid game installers for things like candy crush, Disney magic and march of empire which you can remove easily, but not just "hide" with disabling suggestions.[1]
Yes, I meant disabling "suggestions" stops them coming back again in the future. Although Windows has had update "bugs" whereby this setting is ignored. This is solved by delaying feature updates until at least a week or so after release.
ChromeOS is open-source. Last I looked, their build process was a horror beyond all reason. However, it would at least be possible to strip out any advertising built into the OS. Thing is though, Google controls the advertising on the top two pages on the Internet, and as long as that's true, they don't really need to do anything other than make sure you get there. Which is the strategy behind Google Fiber, Loon, and to some degree Android, more-or-less the reason for Chrome's existence, and why Chromebooks are designed around constant Internet access: all roads lead to Rome.
Yep while everyone was fighting yesterday's war with Microsoft another company took over the internet. Well done guys. Google has more power than MS did at any point in the 90s.
Since Chromebooks are very internet-forward, they get plenty of advertising opportunities without installing banner ads or something similar into the OS. Are you expecting them to start advertising on the Android home screen too?
They already do something better for their ad business moat. They just push their Google Apps bloatware collection on the Android ecosystem at every possible chance they get. I use none of it, yet it still comes with my Samsung phone whether I like it or not. I would expect them to continue that approach with any operating systems they control.
Seems counterintuitive that you take such a strong stance against bloatware and yet use a Samsung phone. The preinstalled (and non-removable) mountain of crap was the reason I gave up on them after my Galaxy S3.
Not that other vendors are much better, mind. But I'm quite happy with my OnePlus for now.
[1] just did a clean install of win10 home