One more thing that we do (or did) in the US was take over terminal airspace that is not open 24 hours. We provided approach control services there in addition to our own terminal areas within our en route (area) sectors. And these sectors are combined and huge for US area sectors. (And still no approach rating.) I've been retired US ATC 8 years but I would bet they still do that.
I never minded, but others refused to ever vector for approach and would require the pilots to fly airways and transitions and entire approach procedures.