I'd imagine it's only as much Linux as Android and FireOS are, which might be argued aren't desktop OSes. But for that matter, ChromeOS might in turn be arguably closer to Android than what would be considered desktop Linux.. (disc: have not used ChromeOS)
I use ChromeOS (Flex on a Lenovo). I believe not counting it as "proper" Linux is more ideological than technical.
Regarding WSL, I have used that too, and happily so. But it's more understandable to count it as not-linux, because of many factors including the Kernel and the file system.
It runs a linux kernel, which makes it a Linux based OS. It probably integrates a lot of linux stuff too, and it of course comes with virtualization support (leveraging the support for this in linux) to run proper linux applications and development tools, etc.
It's big enough to be worth counting separately though. Interesting that regular linux now has twice the market share of Chrome OS.
It still isn't GNU/Linux, and if ChromeOS virtualization counts as Linux, so does WSL, as the technical approach to run GNU/Linux inside its own VM is quite similar in both OSes.
Normal ChromeOS users only have a browser based userspace.
Semantics. GNU/Linux is a subset of linuxes. Chrome OS runs a linux kernel, includes lots of libraries and other things from linux, which, like it or not, makes it another (and pretty significant) subset of linux. Which is why it is counted separately.
Do you think normies are using GNU software on Linux desktops? Or do you think they use software like Dolphin, Nautilus, Steam, Chrome, Firefox, Plasma, etc. A desktop environment doesn't expose GNU/Linux. It requires people to open a terminal to get to it. ChromeOS has its own terminal that uses bash and has its own set of coreutils for people to use.
ChromeOS started as a very weird thing, but increasingly they're moving toward being a reasonably normal GNU/Linux as we know it, with Wayland. And of course a good Android environment.
thing is, on chrome os you can enable debian app support(in two different ways), you basically get both linux apps and android apps, on android it's not that straightforward. Idk how is this done under the hood, but from an user POV chromeos is closer to a windows with wsl2 support with friendlier experience
