I've tried both GDM & LightDM both of which just freeze before displaying

yaml
---
name: brokenone
# description will be included in the image's metadata
description: This is my personal OS image.

# the base image to build on top of (FROM) and the version tag to use
base-image: ghcr.io/ublue-os/base-main
image-version: latest # latest is also supported if you want new updates ASAP

# module configuration, executed in order
# you can include multiple instances of the same module
modules:
  - type: files
    files:
      - source: system
        destination: / # copies files/system/* (* means everything inside it) into your image's root folder /

  - type: rpm-ostree
    repos:
      - https://copr.fedorainfracloud.org/coprs/atim/starship/repo/fedora-%OS_VERSION%/atim-starship-fedora-%OS_VERSION%.repo
      - https://copr.fedorainfracloud.org/coprs/yalter/niri/repo/fedora-%OS_VERSION%/yalter-niri-fedora-%OS_VERSION%.repo
    install:
      - gdm
      #- lightdm
      #- slick-greeter
      - niri
      - alacritty
      - https://github.com/kando-menu/kando/releases/download/v2.1.0-beta.1/kando-2.1.0.beta.1-1.x86_64.rpm
      - micro
      - starship
    remove:
      # example: removing firefox (in favor of the flatpak)
      # "firefox" is the main package, "firefox-langpacks" is a dependency
      - firefox
      - firefox-langpacks # also remove firefox dependency (not required for all packages, this is a special case)

  - type: default-flatpaks
    configurations:
      - notify: true # Send notification after install/uninstall is finished (true/false)
        scope: system
        # If no repo information is specified, Flathub will be used by default
        install: # system flatpaks we want all users to have and not remove
          - org.mozilla.firefox
          - org.gnome.Loupe
      - scope: user # Also add Flathub user repo, but no user packages

  - type: signing # this sets up the proper policy & signing files for signed images to work fully

https://cdn.discordapp.com/attachments/1412947989823225907/1412947990045392976/image.png?ex=68ba25dc&is=68b8d45c&hm=90cdba04bbddeec438d4cc477fa5ccf0f1e5a923575f10df26e358c9a6070b3c&

message has been deleted

Maybe I need some config file to tell it what greeter to use?

It's possible you might have to use the

systemd

module to enable the correct greeter. I've had to do that to get the COSMIC greeter working when I was running just that

tried that, but still no luck. greetd does work though so I might go with that

You don't name the file yourself, you have to find the correct name of the service and add it into that module