Sprinkle 1/2 cup sugar over sliced strawberries in a bowl. Let rest until juices have been released, 10 to 15 minutes.
Boil water and almond milk together in a large pot. Add oats and cook over medium-low heat for 5 minutes, stirring frequently. Stir in strawberries, remaining 1/2 cup sugar, bananas, cinnamon, vanilla extract, salt, and nutmeg and remove from heat. Stir in pecans.
Grease 18 muffin cups and fill each to the top with oat mixture, mounding a bit. Freeze 8 hours to overnight. Remove oatmeal from muffin cups and place in freezer bags or a freezer-safe container.
Prepare 1 frozen oatmeal cup by placing in a microwave-safe bowl and heating in a microwave oven for 1 1/2 to 2 minutes.
