ChimeraOS (previously called GamerOS) is a Linux distribution aimed at full-screen devices and console styled couch-gaming, much in the same way that SteamOS is.
In the years since Valve stopped updating SteamOS 2, ChimeraOS has plugged a rather nice gap for such devices and the developer continues to make improvements. ChimeraOS 27 just rolled out with the usual assortment of main software tech upgrades including Linux 5.14.15, Mesa 21.2.4, NVIDIA 495.44, RetroArch 1.9.11 and more.
Apart from that the main changes for this release include a fix for touch screen orientation on AYA NEO (and potentially other similar devices), a switch from yabause to kronos core for Saturn games (BIOS now required) and it also now skips the Steam startup animation.
So a small release overall but still some nice overall improvements.
What does ChimeraOS look like? Well, if you've used Steam Big Picture, it's just that. The point is to give you a good experience out of the box for controller input and gaming.
You can download from the official site.