Run everything inside your Ubuntu 22.04 proot. I didn't test this yet using chroot.
Addons_Proot_Steam.sh will do this for you. Make sure you run it through Addons_Menu.sh.
Steam Linux on your device using Box86. It requires the use of 'proot' without '--no-sysvipc'.
Sadly, some devices can't run all proot functions without '--no-sysvipc'. You can use two separate proot, one with '--no-sysvipc' and another one without it, just for Steam, using the same distro. This is how I've handled it within the script.
Lack of binfmt can be replace with Boxed bash: https://box86.org/2022/09/running-bash-with-box86-box64/
For now (12 May 2023): it throws 'Fatal error: futex robust_list not initialized by pthreads' error.
See updates here: ptitSeb/box86#770
For now, I don't write a direct guide. Please follow the script mentioned above.
You can install and run the Windows version of Steam through the PlayOnLinux or set it up with already installed Wine. Use "-oldbigpicture -bigpicture -windowed -login someotherusername somepassword" as arguments. Check out here for more support.
Note: oldbigpicture will have low FPS without hardware acceleration.
Example command using system installed wine:
wine Steam.exe -oldbigpicture -bigpicture -windowed -login anonymous
For the moment it doesn't display text, probably due missing fonts, but you can login and use the functions. Installing corefonts (Microsoft Core Fonts) and allfonts through winetricks / PlayOnLinux doesn't make a difference.
winetricks32 corefonts
winetricks32 allfonts
Other options to open Steam doesn't work with the current version, as it open just a black window.