Phoronix article: https://www.phoronix.com/news/Steam-Machines-Frame-2026
Also listed here: https://store.steampowered.com/sale/hardware
Valve has already sent support for the new Steam Controller upstream: https://www.phoronix.com/news/New-Steam-Controller-SDL
I'm rabidly pro-consumer about most things but I struggle with how we define a market when we talk about steam. In order for steam to be a monopoly you have to drill down through super categories of software sales and then video game sales, to the platform level.
If you look at all digital delivery video game sales they still don't have a monopoly. You don't have to deal with steam to play a video game. It's only PC video game sales where they are close to a controlling market share.
But Steam has far less power over PC gaming than Apple, Sony, or Nintendo do over their respective platforms. Gamers and Devs basically HAVE to deal with those companies to have access to their markets.
And even then, most games are available on multiple platforms, for similar prices. So you can get the same game from Steam, GOG, or EGS in many cases, plus all of the stores that sell Steam keys (and Steam probably doesn't get a cut of those sales).