Mix ground beef, oats, onion, egg, water, garlic powder, salt, and black pepper together in a large bowl; shape into 1-inch balls and arrange into a large baking dish.
Bake in preheated oven until very firm, hot, and grey in the center, about 20 minutes. An instant-read thermometer inserted into the center should read 160 degrees F (70 degrees C). Drain fat from the dish.
Stir hot sauce, butter, and honey together in a bowl until smooth; pour over the meatballs. Turn meatballs to coat.