Yes and no.While some of the shipping (and naval support) for DRAGOON was transferred from OVERLORD, don't forget that a lot of shipping was needed for cross-channel supply runs after OVERLORD, especially until some of the French ports were adequately cleared/repaired and regular as opposed to amphibious shipping could be used. While there would be losses from an effective campaign against the invasion ports, a significant percentage of the ships would not be damaged - once it became obvious that things were going badly the ships would simply sail out of range. The Nazis cannot produce enough V1 & V2 and also place launchers in Southern France to deal with dragoon buildups as well as OVERLORD.