In a large mixing bowl, combine one can of crushed pineapple with its juice and one package of instant vanilla pudding mix. Stir until blended and smooth, about 2 minutes.

Gently fold in the mini marshmallows, shredded coconut, chopped nuts (if using), and maraschino cherries until evenly mixed, about 3 minutes.

Fold in the Cool Whip or fresh whipped cream until incorporated, taking about 2 minutes to achieve a fluffy consistency.

Transfer the mixture to a serving bowl or container, cover, and refrigerate for at least 1 hour to set.

Once chilled, garnish with extra cherries or coconut before serving and enjoy.