Barebooting is where you hike without snowshoes or traction aids, usually on packed powder, and only rely on the lugs in your boot soles for traction.It's definitely a workout to walk on snow without snowshoes.
Ok... (being a Finn, I'm trying to figure out how that differs from my everyday hikes during winter. ;)). But my main question is, how would that activity be measured by the watch differently from a regular hike? If everything that's measured is the same, why not just record your activity as a regular hike, and then add a note in Garmin Connect?