You can export it to file whenever you add a new key. Then, use SyncThing to sync the copy to a remote location.
The exported file can be encrypted when you make it.
The exported file can be encrypted when you make it.
I need to do that every time and remember.
From my experience, you loose access when the last backup you made and synced was made before the key you need now was added.
I.e. this doesn't work in practice.