The github docker-compose file calls out pixelfed:pixelfed as the image, but nothing exists when trying to pull it: https://hub.docker.com/r/pixelfed/pixelfed/tags
Is there a official (or unofficial) image that should be used that is compatible with the sample docker-compose setup (and runs on ARM): https://github.com/pixelfed/pixelfed/blob/dev/docker-compose.yml
Looks like that is work in progress and Docker installs are not yet supported by Pixelfed.