Start at Honrich Tower Wayshrine and follow the road going southwest. It will lead you straight to the dungeon entrance.
Once you enter the dungeon, turn left and follow the path. The shard is located inside the first room, in the southwestern dungeon.
Path leading to Avanchnzel.
Dungeon location on the world map.
At the center of the room.
Location on the dungeon map.
Sand Kingdom Moons - Super Mario Odyssey Power Moons