Located in the ruins of Mzulft. You can reach ruins either by going directly southwest of Logging Camp Wayshrine or, if you are in the Jorunn’s Stand encampment, exit through the northern gate and head north. Either way, you will reach the ruins pretty fast. The skyshard is above the entrance and the snow-covered path leading to it is before the entrance, on the right between two stone pillars.
Skyshard on the terrace, above the entrance. Path leading to it is to the right, next to the nearest stone pillar.
Location on the world map.
Jorunn’s Stand northern gate from the terrace above Mzulft.
Sand Kingdom Moons - Super Mario Odyssey Power Moons