Update 23.2 adds a quest line that leads to an instance. It starts with Nain in Jarnfast.
One note: When the quest sends you to Erebor, you may want to use a stable. If you port to the allegiance hall, the quest doesn't advance, so head outside until it says to Seek out Mazalu Ugshar.
The small fellowship instance reportedly has 200 Shadow of Mordor, so you'll need Light of Earendil when you get to it.