https://store.steampowered.com/steamos

Does this mean I can install SteamOS on any device? We expect most SteamOS users to get SteamOS preinstalled on a Steam Deck or device that incorporates SteamOS. The only devices officially supported on SteamOS right now are Steam Deck and Legion Go S. We are working on broadening support, and with the recent updates to Steam and SteamOS, compatibility with other AMD powered PC handhelds has been improved.

If you are interested in installing SteamOS on your device and providing feedback, you can follow the instructions here.

here links to https://help.steampowered.com/en/faqs/view/65B4-2AA3-5F37-4227

With instructions to install steamos and the note:

Currently, the only devices officially 'Powered by SteamOS' are Steam Deck and Legion Go S. We are working on broadening support, and with the recent updates to Steam and SteamOS 3.7, compatibility with other AMD powered PC handhelds has been improved.

So, it's unlikely to be smooth sailing. But it can be done, and steam is working on improving it.

There seems to be some forks out there that claim to improve desktop installation, but I have no idea how active or decent they are.

Personally, I think steam is missing a huge market slice by not creating a steamos for desktops.
However, they don't need it and probably don't want it. It's a market slice in a market they don't need or want: operating systems.
People that would use it likely already have steam on windows. So, it's not bringing in new customers (like the steam deck does).
People that game on Linux likely already use Steam Proton (which is an amazing contribution). So, no new customers by distributing a whole desktop OS.
It's starting a fight with Microsoft (which I think we all want), but with no real benefit to Steam.

I think steam is smart to stay in their lane of handheld OS and Linux tooling for gaming.
Let the desktop gaming distros be maintained by other people. Ideally steam would support those distros, but just maintaining Proton and generally pushing Linux gaming is still a huge contribution.