Are you going to land in Canada because you PR application is approved that's why your asking for Canada or US custom? If you plan to land in Canada, you won't deal with US customs as you going of the US. Hope this helps.
If you are leaving US, you won't deal with US customs or immigration, you only deal with airline officials or if by land, you will deal Canadian border immigration only. So to answer your question, they will not be concerned about your overstay or legal status in the US of A.
