Google have announced that Steam is "coming soon" to ChromeOS - although not before first announcing that it was available now and then backtracking. When it does arrive, it'll be an alpha build only available on some Chromebook devices.
Google mentioned in interviews in early 2020 that they were working with Valve to support Steam on ChromeOS, the operating system that powers their range of lightweight, low power laptops. There was then no further mention of it until this past week, when Google’s product director for games, Greg Hartell, announced during a keynote at Google's Games Developer Summit that "the Steam alpha just launched."
It turns out that was premature. "As you may have already heard, our team is working with Valve to bring Steam to Chrome OS," says a community post from Google. "We are very excited to share that we’ll be landing an early, alpha-quality version of Steam on Chrome OS in the Dev channel for a small set of Chromebooks coming soon. Please come back to the forum for more information!"
There's no official announcements of what Chromebooks will support Steam, but a recently posted code change apparently included a list. It includes Chromebooks from Acer, ASUS and HP.
The fact is that a lot of Chromebooks likely won't be able to run Steam, or to run many of the games on Steam. That's because many Chromebooks are specifically designed to be cheap, low power devices. I used to own a Chromebook that would struggle if I opened more than six browser tabs, although I loved it for many other reasons. This might change in the near future, however, with Google reportedly working on gaming Chromebooks.