Steam is a collection of both 32-bit and 64-bit software. Think of the 32-bit tools as a base that always need to be ran, while the 64-bit tools and libraries are for 64-bit specific tasks. You will need the ability to run 32-bit software, regardless if you are on a 64-bit platform or not. You must also follow the lib32 instructions of each dependency listed unless the section doesn't have those instructions or it is stated to not be needed.
Furthermore, these dependencies are all for runtime. All the tools for the initial installation were built in LFS.
alsa-plugins-1.2.12, cURL-8.13.0, dbus-1.16.2, Display server (Xorg-Server-21.1.16 or Wayland-1.23.1 w/ Xwayland-24.1.6), make-ca-1.16 (with the symlink added), and OpenGL (libglvnd-1.7.0 or Mesa-25.1.0)
Vulkan-Loader-1.4.313 (required for most games), PulseAudio-17.0, xdg-desktop-portal (and a backend service for your graphical environment), Xdg-user-dirs-0.18, Zenity, lsof, and libgpg-error-1.55
LSB-Tools (for Steam surveys)