pearOS NiceC0re (Arch-based)

The [multilib] repository (needed for Steam's 32-bit libraries) is already enabled by default on pearOS - you don't need to edit pacman.conf first, just install it:

sudo pacman -S steam

Launch it from the app menu (or steam in a terminal) and log in.

To run Windows-only games: Steam → Settings → Compatibility → enable "Enable Steam Play for all other titles" and pick a Proton version. This uses Valve's bundled Proton - see how to install Proton-GE if a specific game needs the community build instead.

pearOS Goldwing (Debian-based)

contrib is already enabled in /etc/apt/sources.list by default, which is where steam-installer lives:

sudo dpkg --add-architecture i386
sudo apt update
sudo apt install steam-installer

Same as above for enabling Proton afterwards (Steam → Settings → Compatibility).

If Steam launches to a black screen or crashes on either build, make sure your GPU drivers are actually installed first - see the GPU driver article for your build.