In a large bowl, baking sheet, or air fryer basket, combine the popcorn, almonds, and pretzels.
In a medium pot over medium heat, melt the butter, brown sugar, salt, and vanilla. Bring to a boil and cook for 5 minutes, ensuring the mixture reaches 240°F on a candy thermometer. Stir in the vinegar and baking soda, whisking thoroughly.
Pour the caramel mixture over the popcorn mix and stir until everything is evenly coated.
Transfer the coated mixture to an air fryer basket or tray. Air fry at 250°F for 4 to 6 minutes, stirring occasionally.
Once done, let the caramel corn cool for 2-3 minutes before mixing in the chopped chocolate bar and marshmallows.
Allow the mixture to cool completely, then divide it into lidded containers. Store at room temperature for up to 7 days.