I remember posting one regarding the MERP sourcebook over a decade ago (Maps of MERP: the Scale of Moria), and remember having many questions about that old supplement.
This one is very promising indeed. I have not yet played a single game of The One Ring (though I have both 1st edition & 2nd edition rules), but this may be the book that gets me started. I haven't gone through all of it, but the exploration rules (that were also a part of the main rules in The One Ring) are also applicable to this massive, labyrinthine, iconic place in Middle Earth.
An entire mini-campaign can chronicle the early attempts of Durin to reclaim the mines of Moria, well before they delved too deeply (and too greedily?) and encountered Durin's Bane. It would involve exploring, mapping, and perhaps establishing zones of safety that dwarves (and dwarf friends) can travel to and from as they attempt to recapture and rekindle past glories.