No, Steam comes with everything you need for games. Other launcher work great using Lutris. Apps like Lutris, Spotify Yuzu are on the Discover app store which

No, Steam comes with everything you need for games. Other launcher work great using Lutris. Apps like Lutris, Spotify Yuzu are on the Discover app store which uses flatpak. Flatpak is on many distros already installed or can be installed manually. (PS: The Steam Deck's OS isn't even Arch Linux. It's based on it and uses Arch packages, but updates come from Valve through their own update mechanism with a read only file system. It's like calling Ubuntu Debian just because Ubuntu pulls packages from Debian Testing.)