No, airspeed and/or aerodynamic dont affect the WAAS, LAAS, DGPS, and GPS.
Yep, generally the facts.
Now, lets look at one specific GPS navigation unit installation, the King KLN-89B, installed in my private aeroplane.
Enroute navigatiuon accuracy, RNP 5.
Terminal, RNP 1.
Approach accuracy, +/- nine meters, laterally.
Now, this unit is eight years old, new(er) ones do better.
Quite a bit better.
Fact.
The only reason that the Europeans have not embraced GPS is the old familiar tune....'not invented here'.