It is a stand alone version, the repo contains a binary as well as a logo and shell script for the launcher.
Install with
cd ~/apps/launcher/Menu/GameShell
git clone GitHub - cuu/Pcsx: pcsx rearmed for GameShell
You’ll still need a BIOS file though:
mkdir -p ~/apps/launcher/Menu/GameShell/Pcsx/bios
Transfer scph1001.bin bios file to that folder, restart the launcher and you’re done.
To update the binary in case the repo gets updated, do this:
cd ~/apps/launcher/Menu/GameShell/Pcsx
git pull
When starting the emulator for the first time, you’ll want to configure the controls from the emulator menu because they aren’t setup properly yet.