SnapOptions
You can add SG_SnapOptions to a gameobject that has SG_Grabable. Using this you can define where your hands and fingers will be positioned when grabbing the object.
Note
If you are editing a prefab in a scene, you need to apply the changes or the new hand position will not be saved.
Inspector
Controlls Finger Animation: Allows you to manually define limits or the exact position of the fingers while this object is being held
Pose Preview: Use this to spawn hands and move the hands around to define a position, then store pose when you are done to save the pose.
Reset Pose: Resets position of the corresponding hand as well as its fingers
Mirror fingers: Mirrors the fingers, but not the position, to the other hand
Posing the hand
Using editing the transforms of the spawned hands, you can pose both the position of the hand as well as the position/rotation of the finger. That way you can give a more exact pose for the user of your application to enhance how realistic it looks.