You should ask people from the two offices where it exists. However, we have to be careful. Lobbying is not just done at the level of MPs and ministers. It is also done at the level of senators and departments. I am not at all the equivalent of the Office of the Conflict of Interest and Ethics Commissioner, although I am to some people.
Former public office holders include senators and assistant deputy ministers, who are not necessarily governed by the Office of the Conflict of Interest and Ethics Commissioner.
If you want to consolidate all that into one office, it would be a matter of deciding which one.