SteamOS 3, also known as “Holo,” is a Linux distribution built for the Steam Deck gaming device. The distribution updates itself atomically, meaning it downloads a new read-only root filesystem and reboots into that partition. However, users can also unlock the root filesystem with steamos-devmode to have a normal package manager. SteamOS uses an A/B atomic updates system, which allows heavy customization by the end-user. The author explains their journey of forking SteamOS to make changes to the root filesystem images. The author also shares their experience with the Steam Deck and the benefits of using a Valve-tested Linux distro for gaming.
https://iliana.fyi/blog/build-your-own-steamos-updates/