Skyshard is located on top of the right corner of the structure with the door, as pictured in the screenshot above.
The shard is in the west part of Glenumbra Moors quest area. It is on top of a structure inside which is a door that later takes you to do part of the quest here.
Note: I don’t think you can reach this position other than going through the entrance of Glenumbra Moors. Marked on the screenshot above is both the entrance and the skyshard’s location.
Sand Kingdom Moons - Super Mario Odyssey Power Moons