Valve has been building up to this for months, first in preview, then in beta, and now finally in a full stable release: a new version of SteamOS that brings brand-new features to the Steam Deck and supports third-party handhelds like Lenovo’s Legion Go and Asus’ ROG Ally series.SteamOS 3.7.8 is the first stable release to add official support for the Lenovo Legion Go S, and the first to offer an official “recovery” image that lets you install SteamOS on other AMD handhelds like the ROG Ally and...