Once upon a time, listing everything installed on your system was simple. You had a package manager and that was it. Nowadays, normal systems often have multiple additional installation channels
Inventory gives you a unified listing spanning all installation channels. It queries using apt, pacman, dnf, zypper, apk, emerge, xbps, flatpak, snap, pipx, cargo, gem, yarn, pkg, npm, homebrew, and nix.
Normally tries to skip packages in your system base, but you can override this.