Which basically means being able to have a GNU userspace, which neither Android nor ChromeOS do.

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.

Interesting sidenote: both ChromeOS devices and iOS devices (and, to some extent, macs), as well as all consoles, are sold as single bundled hardware+software integrated products.

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.

Already is. There must be more smartphones and tablet users than personal computer users in the world. Simply because a person who use a PC but doesn't have a smartphone (hyper nerds like Stallman, or ppl who have very particular jobs that give them the freedom not to have a smartphone) are outnumbered by those who have a tablet or smartphone but not a PC (my 94 year old grandma)

The majority of smartphones, I believe, can have other software loaded on to them, if the user so desires.

Yes, but most of the time you're bound to proprietary blobs or some things won't work.

True, but consider that the vast majority of Android users have no clue how to do that.

This already happened for most developers who are the last real users of PCs.

WSL is microsoft giving up. Other users dont really need PCs any more, you just use a phone or a web browser.

I don't know if WSL is Microsoft giving up or Canonical. It just gives people an excuse or a reason to use Windows.