Google thinks it's a street, and it looked like one for about half a block, before I reached this mess. But it connects through to a real street on the other side, and there were no signs marking it as private property, so, just to be safe, I "walked" it.
It’s the pits.
There seem to be a number of “streets” in this area that are, on closer inspection, more or less impassible (e.g. Stewart between Anthony and Cherry, Varick between Lombardy and Maspeth). But you’re doing a better job of covering them than the Streetview car. Keep up the intrepid exploring!