Federal prosecutors have charged Amardeep “Bobby” Singh with violating the Defense Production Act of 1950 for allegedly hoarding personal protective equipment, including N95 masks, face shields, gloves and disinfecting products, and selling them at huge markups. Mr. Singh, who sells sneakers and apparel at his store on Long Island in New York state, acquired face masks for seven cents apiece and resold them for $1, according to prosecutors. Mr. Singh’s lawyer described the charges against his client as being “mostly fiction.”