Line a large rimmed baking sheet with parchment paper.
Combine the Chex cereal, pretzels, almonds, peanuts, and pepitas in a large bowl and set aside.
Melt the butter in a small saucepan over medium heat.
Continue cooking, swirling the pan occasionally, until the butter turns golden and smells nutty, about 4 to 5 minutes. Remove from the heat immediately.
Whisk the fish sauce, smoked paprika, sumac, garlic powder, cayenne, and kosher salt into the brown butter.
Pour the seasoned butter over the snack mix and toss until everything is evenly coated.
Spread the mix in a single even layer on the prepared baking sheet.
Bake for 1 hour, stirring every 20 minutes, until dry, fragrant, and lightly crisped. Remove from the oven.
Immediately drizzle with hot honey and toss to coat.
Sprinkle with flaky salt.
Spread back out on the baking sheet and cool completely before serving. The mix crisps further as it cools.