If you skip the MANIFEST_URL it will skip downloading manifest from remote location and directly use the MANIFEST_PATH. Note that MANIFEST_URL variable will be deprecated as soon as the manifests from the kde-flatpak-manifests will be merged in the individual repositories.
Gitlab CI currently allows building flatpak on experimental basis. Overall recipe for the snap builds is subject to change. Currently ange-lxd builder is capable to build snaps.
Add binary-snap.yml template in the your .gitlab-ci.yml
You can learn more about Gitlab CI from the links in Resources section.
Acceptable usage policy
For frameworks, applications, and other repos which are used by other projects you can add your own builds, but you can't remove the KDE CI configuration. This is to ensure that, your project artifacts are available to projects which are using your project as dependencies.
Gitlab runners are using the docker executor, which generally speaking have needed security measures, but any attempt to circumvent the security will be considered the violation of code of conduct.
If you're considering to add the builds which take large amount of time (> 30 mins) on shared runners please talk to us beforehand.