Start at Trolhetta Wayshrine. Follow the road going northeast and at the first crossroads turn left. At the second crossroads just continue forward and you will soon stand right in front of the dungeon entrance.
This and all other shards inside solo dungeons have had their locations changed due to post-launch dungeon remodeling. This one was relocated to the eastern part of the cave. This is the brightest part of the cave, since the ceiling is broken and the sunlight enhances the glow of the shard.
Dungeon entrance. The other path will lead you to the Walk above the clouds skyshard.
Dungeon location on the world map.
In eastern part of the dungeon.
Location on the dungeon map.
Sand Kingdom Moons - Super Mario Odyssey Power Moons