As seen on Reddit, it is possible to sync all and any preferences across devices with a Firefox account.
services.sync.prefs.sync.preference_name = true
So, perhaps this site could add an extra checkbox (opt-in) next to all settings so that the user could also sync the defined setting? Maybe even a button in Finish to sync/not sync all settings at once.
As seen on Reddit, it is possible to sync all and any preferences across devices with a Firefox account.
services.sync.prefs.sync.preference_name = true
So, perhaps this site could add an extra checkbox (opt-in) next to all settings so that the user could also sync the defined setting? Maybe even a button in Finish to sync/not sync all settings at once.