If you're running my fork of illogical-impulse, you can install this from the Settings app (System -> Advanced).
If you're using an unmodified version by end-4 or other DE, you can use install.sh script.
Important
You need to manually install these packages using your distribution's package manager:
jq, greetd. Install greetd-agreety if Agreety is not bundled with greetd by default (typical on Arch)
If you're not using illogical-impulse, you'll also need to manually install fonts (Material Symbols Rounded, Google Sans Flex, Space Grotesk)
and Hyprland 0.55 or newer + Quickshell. Refer to sdata directory in illogical-impulse repository.
mkdir -p ~/.cache/ii-greeter
git clone --recurse-submodules https://github.com/Vercixx/ii-greeter.git ~/.cache/ii-greeter
cd ~/.cache/ii-greeter
sudo ./install.sh
Then, disable any existing DM in your init and enable greetd
You can uninstall greeter with:
cd ~/.cache/ii-greeter
sudo ./install.sh uninstall
Make sure to enable another DM, so you don't get dropped into bare tty!