There was a case in a in a session of my Homebrewy D&D 5e game that I played recently where I was playing a Gloom Stalker Ranger lvl 4 and was hidden from an enemy that was unaware of an incoming attack. In the spirit of the ambusher that is the Gloom Stalker my DM allowed me to role the extra d8, normally granted to me by Dread Ambusher feature on the bonus attack that I would get on the first turn of initiative order, for the damage that I dealt to the creature; similarly to a rogues sneak attack.
Should a Gloom Stalker Ranger always get a additional d8 when attacking an unaware creature outside of initiative order?