Spread a couple sheets of parchment paper, wax paper, or two silpats on the countertop then set aside.
Add puffcorn, pretzels, and peanuts to a very large bowl - if you don't have an XL bowl, use two large bowls - then set aside.
Add chocolate chips and coconut oil to a medium-sized, microwave-safe bowl then microwave for 40 seconds and stir. Microwave for 30 seconds then stir. If chocolate chips aren't completely smooth, continue microwaving in 10 seconds increments, stirring between increments, until completely melted.
Drizzle chocolate over puffcorn mixture then gently fold with a spatula until everything is evenly coated. Spread mixture out onto prepared surface then sprinkle with M&Ms (may not use whole bag) and press gently so they adhere to the warm chocolate. Add sprinkles then let cool completely. Transfer to treat bags or an airtight container.