I will assume that by “pivot point” you mean the origin.
I think it would make more sense to refer to Transform Pivot Point when you say “pivot point” in Blender.
Geometry nodes use object space to place geometry so I don’t think there is an elegant way to change the origin of object space without changing the position of geometry generated by geometry nodes, unless it uses something else for its position(like another object for example). If all the not so elegant ways could work depends on your specific workflow and why you need this.
I think depending on the workflow it might be easier just to parent the object to something else like an empty and use that for whatever you need.
You need to use the self referencing to get the updated location, then subtract the location from the original location, or offset with a transform node.
There are also matrix nodes in 4.2 which could help with simplifying more complex transforms.