Vegan Pistachio Shortbread Cookies

Name: Vegan Pistachio Shortbread Cookies
Ingredients: 0.25 cup water; 0.5 teaspoon agar-agar powder; 0.5 cup vegan butter, at room temperature; 0.5 cup solid coconut oil; 0.75 cup powdered sugar; 1.5 cups brown rice flour; 0.5 cup finely ground pistachios; 1.5 teaspoons vanilla extract; 0.25 teaspoon salt; 3 tablespoons aquafaba (chickpea water); 1.5 cups powdered sugar; 1 tablespoon rose water; 1 cup finely chopped pistachios