This person, who identifies as male, was a gunner for the Rebel Alliance. Serving under the command of Captain Miara Larte, he was not on Alderaan, his homeworld, when it suffered destruction. During the Royal Award Ceremony in 0 ABY, he was at the Great Temple located on Yavin 4.
Miara mentions in "By Whatever Sun" that the gunner's name is something along the lines of 'Hester, Heattens, or a similar name'.