At least for Bazzite, Nobara and CachyOS, there is the SteamOS desktop option that boots directly to Steam's Big Picture that is quite unconventional in some ways (e.g. this desktop mode kinda also acts as a display manager, so there is the option to boot to your desktop from Big Picture mode and this option is generally broken without specific integration with the session manager).

Sure this could probably be a package in a more "traditional distro", but I'm almost sure most people don't expect their Display Manager to be replaced with Steam when they install a package.