If you know how, there's an escape hatch. There are basically multiple filesystem trees under the hood (shared with hard links to avoid duplicating file data),

If you know how, there's an escape hatch. There are basically multiple filesystem trees under the hood (shared with hard links to avoid duplicating file data), and at boot time you'll get one of them. These are known as "OSTree deployments", and they're found in /ostree/deploy, and they're actually mutable, it's just the bind mounts into that location that are mounted RO. Anything in the bootloader configuration is not part of the deployment (from what I remember), and so it's mutable. See the docs here: https://ostree.readthedocs.io/en/latest/manual/deployment/ https://ostree.readthedocs.io/en/latest/manual/deployment/