In a 16-ounce glass jar or airtight container, combine the rolled oats, chia seeds, and chopped pistachios.
Add the almond milk, Greek yogurt, sweetener, vanilla extract, and salt.
Stir the mixture thoroughly until no dry pockets of oats remain and the yogurt is fully integrated.
Seal the container with a lid and place in the refrigerator for a minimum of 6 hours, or overnight, to allow for complete hydration of the grains.
Remove from refrigeration, stir once more to redistribute any settled liquid, and serve chilled.