German mag pcgameshardware (translation):

Following the excitement surrounding the surprise announcement of the Steam Deck OLED, which has now been officially released, more questions have been raised about the possible release of SteamOS for other systems. Several Valve developers commented on this topic to the website Gizmodo and said that SteamOS 3.x for other systems would be “at the top of the list”.

…

The developers also announced that the free operating system, which is based on Arch Linux, known for its timeliness, and the highly customizable desktop KDE Plasma, will be released first for other handheld PCs and only then for other systems such as desktop PCs and notebooks.

We’ll probably start by making it [SteamOS] available for other handhelds with a similar Gampad controller. And then beyond that, for any device.

- Lawrence Yang, Valve -

The background is basically self-evident, SteamOS in its current form is customized for handheld PCs in general and the Steam Deck in particular. Most of the work is on the drivers for hardware support, which is one of the reasons why Windows 11 is still struggling with handheld optimizations.

I think the biggest issue is driver support and making sure it works on every PC it lands on.

- Lawrence Yang, Valve -

Source (German): https://www.pcgameshardware.de/SteamOS-Software-258049/News/SteamOS-auf-anderen-Systemen-1434178/