To install from source, you will need libpam0g-dev on debian.
For using gtkgreeter, you will also need libgtk-3-dev, libjson-c-dev.
For building gtk-layer-shell, you will need to install:
sudo apt install meson libwayland-dev libgtk-3-dev gobject-introspection libgirepository1.0-dev gtk-doc-tools valac