together with the integration for the Community Editions (sway Bspwm) we do implement an option to the ISO what will make it possible to install any DE/WM by providing a packagelist and a setup script.
For a template simple take a look at the sway one:
mainly two files are needed:
Packages: https://github.com/EndeavourOS-Community-Editions/sway/blob/main/netinstall.yaml
Setup: https://github.com/EndeavourOS-Community-Editions/sway/blob/main/setup.sh