BlueBuild

with the help of you kind people I was able to setup my github repository. I am using ghcr.io/ublue-os/bazzite-nvidia as the base image.

Unfortunately 

  - type: dnf
    install:
      packages:
          - firefox

fails at the same point that started this endevour: There seems to be a dependency conflict with mozilla-openh264. This Package seems to be sourced from the repository fedora-cisco-openh264. The bazzite base image includes openh264-1:2.6.0-1.fc43.x86_64 but mozilla-openh264 requires openh264-1:2.6.0-2.fc43.x86_64 .

Any Idea on how to get this to work?

You need to enable the repo that provides openh264. Bazzite disables several repos by default so this is likely an effect of that
Try adding 

```
repos:
  nonfree: negativo17
```

before install. my formatting might be off though so check the dnf module docs to be sure

So it would end up looking like
```yaml
- type: dnf
  repos:
    nonfree: negativo17
  install:
    packages:
      - firefox
```

Then you can add whatever package you need from the negativo repos