Bazzite isn't an exact clone of SteamOS 3, but its functionality is virtually identical to Valve's operating system. On the surface, Bazzite features an identical desktop experience to SteamOS 3. Thanks to the integration of KDE Plasma — a customizable Linux desktop environment, and Valve's KDE themes from SteamOS, Bazzite shares the same desktop wallpapers, icons, and taskbar as Valve's operating system. If you didn't know any better, you'd think you were running the real SteamOS.
But under the hood, Bazzite's actual operating system is not the same, as it uses an entirely different Linux distro from Valve's operating system. Instead of using a branch of Arch Linux, which is the distro SteamOS 3 is based on, Bazzite is built using a custom version of Fedora 38, which incorporates more hardware and device support than SteamOS 3. Some of the hardware support includes baked-in proprietary Nvidia driver support for GeForce GPUs, to enable GeForce-powered systems to run Bazzite. (Sadly AMD support is unclear — but the OS does support AMD ROCm.)
I have used ublue os before it started to gain popularity. It's basically fedora silvervlue with different desktops made available.
It's pretty good for an immutable system and worth checking out.