ChimeraOS Linux 45-1 is out now as a minor update to the current release, but it still comes with a healthy dose of handheld gaming improvements for people who don't want Windows.
While Valve still haven't released SteamOS 3 for download to other devices, the Linux community continues to show off how great open source is. ChimeraOS is an operating system that provides an out of the box couch gaming experience. Once installed, it will boot right into Steam Big Picture for a good handheld interface, and it comes with many additions for various handhelds.