I think it might be good to stand back a bit and think through what we are actually excited for. Because:

1. if someone uses Linux Desktop without caring about that it is Linux, why is that different from them using Windows? 2. why do we say SteamOS count as Linux Desktop but Android doesn't? is it really because how much of it is "Linux"?

For me, I think what matters to me is who has control over it. SteamOS is based on Arch, so the community has a say over where it will go, and Valve will have to work with the community. Android/Windows are fully controlled Google/Microsoft, doesn't matter that Android is Open Source.

As a user, what usually matters to me is what software I'm able to run on it. So even if people don't actually care about the OS itself, they will care that X runs on it but Y doesn't, which, given enough users, may push X to support that OS.

I actually daily drive Linux (Arch) because Windows is a PITA I'm not willing to put up with. But there are things I use which still don't run on Linux (Photoshop and Lightroom), so I'm actually thinking of getting a Mac again instead of having a second PC / dual boot, even though I know that can also be irritating (though less so than Windows).

"Who controls the OS" isn't that important to me. What matters is that it gets out of my way and lets me do what I want to do with as little friction as possible. I know Linux being free means I can go and hack on it however I like. But I also have to contend with reality: I can't reasonably think that I (personnally) am going to hack on the kernel or on some desktop environment in any meaningful measure, so I still have to put up with whatever other people figure is best.

But if there are enough people like me, including those who don't actually care about what OS they're running, maybe the apps I want to run will adopt Linux. But that only matters because, as it turns out, it's the OS which I find the less irritating to use. If tomorrow Windows 12 finally became sane, I'd switch in a heartbeat. I'm not married to Linux.

If someone runs Linux Desktop without caring that it is Linux, it still means that they use software that runs on Linux. Say if governments move to some Linux distro, they will need an office suite, and they may pay for its development.

If someone runs SteamOS, it means that they play games on Linux. So it becomes interesting for game devs to test for Linux. And then if someone runs SteamOS, instead of a dual boot with Windows maybe they just go to the Desktop mode. Which means that instead of Microsoft Office, they use something that runs on Linux, etc.

This is good for the Linux ecosystem. And the reason I like the Linux ecosystem is because, as you say, it's not fully controlled by TooBigTech.

I'd start that conversation from another perspective. If someone uses linux, not caring that it's not windows, then that's a milestone.