The short answer
Yes, on a clear night without much moon, once you step away from the camp lights. The deep desert at Merzouga and especially Erg Chigaga has very little light pollution. The clearest skies tend to come between late autumn and early spring, and a night near the new moon is best. Agafay is good too, with some city glow.
In more detail
The Milky Way needs two things: dark ground and no moon. The dunes give you the first. For the second, check the moon phase for your dates before you book; around full moon the dunes are bright enough to walk without a torch, which is lovely in its own way but washes out the faint stars.
Erg Chigaga, far from any road or town, has the darker skies of the two great dune fields. Erg Chebbi has a village and a road along one side but is still excellent once you are behind a dune. In the Agafay the sky is dark enough to impress, though Marrakech lights the horizon on one side.
Winter nights are often the clearest and the coldest, so dress warmly. Ask the camp to turn off the generator or the path lights for a while if they can, give your eyes twenty minutes to adjust, and leave the phone screen off.