Heat oven to 350° F. Spread the coconut on a rimmed baking sheet and toast, tossing occasionally, until golden, 6 to 8 minutes; let cool.
Meanwhile, with an electric mixer, beat the cream with the salt until soft peaks form. Gently fold in the dulce de leche. Divide the mousse between bowls and chill for at least 45 minutes and up to 8 hours. Sprinkle with the coconut before serving.