SteamOS, Valve's Linux distribution aimed at a more console-like big TV experience actually saw some small updates recently.
Firstly, the 2.166 beta that was released way back in August of 2018 was finally promoted to the stable channel so you don't need to mess about with opting into the SteamOS beta. This is important, since it brings with it an updated NVIDIA driver, an updated Mesa driver, security fixes and a bug fix for an unresponsive login button.
The extra importance of those driver updates, is that they're the absolute minimum required for Steam Play use. Still, they're obviously quite outdated now since there's been a number of big updates since August last year.
It seems to have gone a little unnoticed, with a new 2.170 SteamOS beta that went live earlier this week too. Although, it's nothing fancy with only security fixes being noted. Even so, it's good to see some work being done on it.
Hopefully later this year we will finally see SteamOS 3.0 codenamed Clockwerk, with it being based on Debian 9. Their repository list doesn't show it seeing any updates since last summer though, so hopefully it will be picked up again.