Although it may be considered as being hidden, its name reveals everything you need to know about its location. There is a nearby city called Morkul Stronghold. The seaside view suggests it at least has some view of the nearby sea.
It all comes together once you find it on a small wooden deck, high tide pier, just west from the stronghold. There is a strangely beautiful house rooftop nearby, that almost reflects the close by sea. It is as it was designed to lower the pressure from the wind coming from the sea.
Sand Kingdom Moons - Super Mario Odyssey Power Moons