Hi there! Stumbled across your project trying to set up an AO3 -> Calibre -> eReader pipeline for a fic that I read, and went to try setting up a POC on my laptop. I run an Apple Silicon Mac, which uses arm64. I noted that your GitHub Actions are set up to build for linux/amd64 and linux/arm64, however the arm64 targets seem to be published to GHCR as unknown/unknown. There may need to be some update to your actions to ensure these are tagged appropriately.