Several companies have made guns with .50 smooth bore barrels in the past including Lyman and CVA.
They usually have adjustable rifle sights and are considered to be smooth rifles. They're not really popular barrels and were limited offerings.
This is the first TC .50 smoothie that I've heard about and could be fun if you don't mind its effective range being limited to more moderate distances.
The TC .56 smooth bore is known to shoot as accurately as any rifle at 50 yards with tightly loaded PRB's.
Hornady makes easier to load .480 balls for use with a thicker patch.
When loaded with shot it would be more like a .410 shotgun which is for fairly close range especially if it's without any barrel choke.
And then there's always the possibility of loading multiple buckshot much like commercial .410 shotshells offer, or a buck & ball type load.