Looking at Harbor's art released today, the water sphere behind him emerging from the wall has an interesting detail - if you zoom in you can see some distinct circular ripples which look identical to the ripples when Astra's wall blocks bullets. This property of his kit is also backed up by the Skye voicemail in The Range a few weeks ago where she describes bullets landing in a semicircle on the floor.

This confirms that along with his wall smoke, Harbor also can create a sphere which blocks bullets. My assumption is that this sphere is transparent but it could also double up as a smoke instead, making it a mini Astra ult.