You’re looking for Claw’s Strike solo dungeon to collect this shard. Main road east of map marked position leads to this location. This is a an old temple with cellar doors inside the main building that lead to the dungeon. Inside the dungeon you can find groups of maximum level 40 Dawnmead mobs.
Once you enter the dungeon, turn right and follow the path.The shard’s location is in the western room. The dungeon boss, Fishbreath, is in the opposite, southeastern part of the cave.
Claw’s Strike solo dungeon.
Claw’s Strike entrance.
Claw’s Strike entrance map.
Sand Kingdom Moons - Super Mario Odyssey Power Moons