I'm not sure that comparing Linux to Windows 10 (or 11) is fair in the sense that most 'normal' users are not willing to jump through all of the hoops required in order to get a usable desktop environment without much effort and tinkering
The beauty of Linux, the fact that it is endlessly customizable and can be altered to fit an advanced power user's needs perhaps also remains its Achille's heel as most people out there who just want to turn the box on and for it to work, with simple, widely-accepted solutions available beyond the OS itself. While the last ten years have obviously seen much progress towards this goal (Arch, Mint, even Ubuntu, as well as LibreOffice), it still remains that widespread adoption is only going to happen when there is a giant effort to standardize things and dumb them down more than a bit. The percentage of users who want to do pull requests from GitHub to patch or update a system, or deeply care about the privacy of their data probably is less than 10% of the general population.
While I'm sure there are great self-hosted systems out there that can rival the ubiquitous convenience of a turnkey solution like 365 which seamlessly (in theory) makes your data available across multiple devices including mobile whatever the OS may be, until a credible open source version of it can be proven to be as reliable and convenient (including in workgroup environments, not to say anything of enterprise level of rollouts) I'm not sure it's something that makes the case for large-scale adoption.
Yes, if a country's police department can find the funding to hire a developer to customize and maintain a distribution to their needs, and possibly spec out specific hardware that makes it possible to get it working reliably, then such a use case makes total sense.
But until this happens for an entire country, I'm finding it difficult to believe that it'll happen on its own otherwise. Normal users want support, hand-holding and pre-built solutions with limited choices and good security that works on the hardware they use. In other words? This happens to exactly be what OS-X brings to the table, even though in this case the OS is a commodity which is only there in order for Apple to make money from selling their hardware.
So maybe the real question is: can something like OS-X a.k.a. "It Just Works" be developed for Linux on specific hardware, and all of it be open-source? I'm sure there must be many reasons that it hasn't happened so far. SteamOS looks to be the one that's the farthest along in following this path, because they've eliminated so many of the available choices in order to provide users with a system that just works. This is only possible because Steam monetizes the games it sells, and the OS (once again) is a necessary loss leader.
Google could easily do it, but have no incentive to do so because they would only be interested if they could use the platform to harvest data and spam ads.
France sort of did something like this 30 years ago with their 'Minitel' which was a small form-factor dumb terminal computer that made using the phone system pretty amazing back then. It made sense because the phone company was using it to sell more phone calls. Maybe once an entire country decides to commit resources to a giant effort like this, it can have the effect of creating the kind of critical mass adoption we're all wishing for? Not impossible, but where does this exist? Among the many other hidden costs, someone still has to pay for all of the developers and for the update, support and maintenance for all these systems.