Here I will teach you how to make steam deck's desktop mode actually usable.
By default, you can only install flatpaks, which extremely limits the possibilities of your computer (steam deck is a computer, don't forget)
I myself have been using steam deck as my main computer for about 3 months now and while at first I mainly used windows on it,
I soon realized that I could utilize Linux without sacrificing functionality.
Bofore each set of command there will be either Host (SteamOS) or Guest (Inside a distrobox distro). If after the command you see Host, run it inside your ususal terminal, if inside of Guest, you'll first need to distrbox-enter yourdistro
Install podman and distrobox.
Distrobox acts as a linux distribution inside a linux distribution. You can, for example, have an arch based distribution and install ubuntu based distribution with full support for GUI applications. It transparently mounts your user's home directory in a sandbox,