A Seaford man was charged with drug possession as part of a large-scale narcotics investigation that led to the indictment of six people accused of trafficking fentanyl, cocaine and xylazine throughout Nassau County, prosecutors said. Joseph Giunta, 76, of Seaford, was arrested June 24 and arraigned Sept. 4 on charges of third-degree criminal possession of a controlled substance and seventh-degree criminal possession of a controlled substance. H…