Where to get OVRSpatialAnchor when loading unbound anchors?

I'm able to create and re-load spatial anchors, but when I reload the unbound anchors I'm unclear on where to get the OVRSpatialAnchor from.

The docs say to bind to an OVRSpatialAnchor after Localized. In the sample it looks like this:

var spatialAnchor = Instantiate(_anchorPrefab, unboundAnchor.Pose.position, unboundAnchor.Pose.rotation);

I'm unclear on where the _anchorPrefab is coming from though as that is also an OVRSpatialAnchor. Is there a way to do this that doesn't use a prefab? When I create my original game object and anchor I'm doing it this way:

var gameObject =
GameObject.Instantiate(Resources.Load<GameObject(gameObjectPath),
worldObjectPose.position,
worldObjectPose.orientation);

var ovrSpatialAnchor = gameObject.AddComponent<OVRSpatialAnchor>();