If `extensions.pocket.enabled` doesn't sync (I don't know if it does by default), consider adding `services.sync.prefs.sync.extensions.pocket.enabled`, then it will synchronize across devices.
Bookmark sync is currently getting a complete overhaul to fix the various shortcomings: https://docs.google.com/document/d/1WoM7JEatr_QJ1CrGk2rwoSDy...