As far as I can tell, Chrome OS is the Linux desktop and the GNU user space. The user space may not be exposed by default, but it is there. It may not be considered complete by those who expect compilers and X to be installed by default, but those tools can be installed since the underlying infrastructure is in place. It is not another Android where, as far as I can tell, very little of the GNU user space is in place.
Having to switch into developer mode (on older Chrome OS devices) or run Linux applications is a sandboxed environment is beside the point. These are just a security model layered on top of the OS.
On Android, Linux kernel is an implementation detail not exposed to userspace APIs as official stable APIs, even for basic stuff like bluetooth or accessing files outside the sandbox, Java APIs have to be used.
Then on the ChromeOS side, not all Chromebooks support Linux based applications, and even that is actually a design similar to WSL 2, by running it into another VM on top of the Linux kernel used by ChromeOS.
There's very little computing done where the hardware is not designed with the software in mind and vice versa.
The days of "software x running on hardware platform y" might be behind us for the majority of the planet's population.
WSL is microsoft giving up. Other users dont really need PCs any more, you just use a phone or a web browser.
ChromeOS is as much a Linux computer as is a Tesla automobile. Sure, there's a linux kernel down in there somewhere, but it's not the thing we mean when we say "Linux Desktop".