There is a python3 problem with Docker images of snapcraft other than stable. I added CI to catch these errors.
https://github.com/snapcore/snapcraft/pull/2851
There is also PR for making snapcraft images for custom Ubuntu version and risk without creating new Dockerfiles.
https://github.com/snapcore/snapcraft/pull/2673
And I can add audodeploy of images to Docker Hub if needed.