It requires an attack roll... but is limited to the weapon's range. Spell sniper only really modifies spells that have a range, and GFB is definitely "Your weapon's melee reach, and nothing more." So you can get a target 10 feet away... but you need a reach weapon, not the feat.
However, it might make the secondary target of the ability easier to reach, given that is a range of 5 feet instead of range: melee weapon attack. Hitting the initial creature, and then a target up to 10 feet away, instead of just waiting to be surrounded completely/ restricted to the horde being all around you? Yes please.