Geometry Nodes Constraint

Why can't we have a Geometry Nodes Constraint similar to the Armature Constraint? Although the Armature Constraint is almost identical to the Armature Modifier, the kind of GN Constraint I'm thinking of will connect to an existing GN Modifier by inputs. The data from the GN Modifier will be transferred to the GN Constraint. There may need to be a unique output node or a custom transformation matrix attribute to be outputted from the GN Modifier for this to work. But if it does, we can manipulate outside objects such as Lights, Cameras, Empties, etc. from Geometry Nodes.

Also, if this GN Constraint exists as a Bone Constraint, you can solve one of the long-standing requests of incorporating Geometry Nodes into Armatures. You could potentially manipulate a Rig from the Mesh through the GN Modifier. Poses could be constructed as non-destructive, procedural, GN Modifiers. They would be stackable and can be controlled by values in the properties editor. Likewise, you don't need the pose library add-on to make a GN Pose into an asset since GN node trees can already be made into assets. For modeling you can make changes 'after' rigging because the constraint may allow manipulation through its 'child'. This seems more complicated since I didn't work out the conflicts between a deformation object and its object.

However, how hard could this be? It's a constraint so, it will only make transformations.