Yes, you can charge the Samsung Galaxy Watch Ultra with the Wireless Charger Pad Trio. The charger supports charging Galaxy Watch models, including the Galaxy Watch3, Watch Active2, and Watch Active. Although the Galaxy Watch Ultra is not explicitly mentioned in the lists of compatible models, it is likely that it is also compatible as it uses the same Qi charging standard as the other Galaxy Watch models.

However, it should be noted that the right pad of the charger is specifically designed for Galaxy Watch models such as the Watch3, Active2 and Active, and there is an internal magnet that guides the Watch into the correct position.