Many of these might actually be considered nicknames more so than given names. Most Americans are not big fans of this style of names, however in England and Wales, names like Effie and Alfie are considered full, stand-alone names and rank fairly well on the popularity charts.
Girl names ending with -fy and -fie:Buffy
Boy names ending with -fie:Alfie
Girl names ending with -gy and -gie:Margy
Boy names ending with -gy and -gie:Iggy
Would you ever use any of these names as a full given name on the birth certificate? If so, which one?