Hi @timconsidine , I know I won't have time to do a PR anytime soon, so I'll drop a note here. Huge kudos on bringing the package forward.
The Garage state is stored entirely in SQLite databases. I can't remember the names of them... there's 2 or 3? So while you've spec'd the directories where they will live, that's only part of what needs to be done with them for a restoreable Garage installation on Cloudron.
https://docs.cloudron.io/packaging/addons/#sqlite
You'll want to make sure they're explicitly called out in the manifest. Doing so makes sure they get baked up safely.
If you don't, it is possible that a backup will fail to correctly capture all of the metadata about the Garage instance, and the result could be lost data upon restore. (That is, if a WAL file is not flushed, then the standard backup might capture the metadata DB in an inconsistent state, and if someone had to restore, they would have a corrupt and unrecoverable Garage installation.)