Reading the FAQs, the whole situation smacks of changing for the sake of change. It seems like some important functionality of the old system isn’t available in the new system, but they’re pushing it through regardless. Combined with this downplaying of Linux support, perhaps some political representatives with low technical skills have been talking to some lobbyists. And unless the Finnish school system has bought into Chromebooks in a big way, they seem unusually eager to support ChromeOS.

I wonder if the whole Secure Boot/Microsoft shim key issue is a part of this.

This is another good point. I’d try turning off Fast Startup first, and if that alone doesn’t clear the issue, try this (leaving Fast Startup off).

Make sure that Windows Fast Startup is turned off. I don’t know if that’s specifically the problem here, but in my experience quite a few “everything’s fine, it should be working!” boot issues have been resolved by booting into Windows, turning off Fast Startup, and then doing a full shut down before going back to Linux, especially on laptops.

“Windows has inconsistency with icons and design in some areas.”

I prefer Linux, but what? Oh, hello pot! Have you met my friend kettle?

Maybe they believe that most of their customers don’t really know much about computers beyond turning them on and “bigger nunbers = better”. They might not be wrong.

I haven’t done it myself, but briefly flirted with the idea a while ago. This seems to be a solid guide, including tips specifically for the Surface Pro 8:

https://github.com/linux-surface/linux-surface/wiki/Installation-and-Setup