Hi @ecovalence,
We do not currently support syncing one linked storage to another, directly. It is something that has been requested, but not planned for, at this time: Moving, Copying and Auto-Syncing Files Between Services (Clouds)
You can sync external storage, like external drives and mounted networked storage using the “sync to odrive” feature: https://docs.odrive.com/docs/manage-sync#section-syncing-external-storage