If you're going to seal it you'll probably want to clay it. Sealants don't like to bond to waxes, which is probably what your dealer used. If you want to skip the clay you can lightly mist some alcohol/water (50:50, regular isopropyl alcohol) on the car then wipe it off (wash first), then seal it. Wax is optional if you use a sealant.
I've not used either of those products, so I can't really say.