How do I get my home-popped popcorn to be as dry as bagged popcorn? When using an air popper to pop popcorn, it never seems fully dry as the healthier bagged popcorn from Smartfood, Skinny Pop, etc.

Before putting any toppings on the air-popped corn, I taste some of the plain popped corn and it seems to still have some moisture content.

I've tried to place the popped popcorn on a sheet pan in the oven at 200°F for a while in an attempt to dry it out further, but it never seems fully dry.

My wife makes kettle corn using oil, sugar, salt, and popcorn and it turns out much drier… but then it also has a salty-sweet coating. Perhaps I have to kettle pop plain popcorn to get a drier result?

How do I make really dried out popcorn?
The problem is not water content but mouth feel, smartfood and skinny pop are coated with a fine powder which has a dry mouth feel. You can dry your popcorn as long as you like but you'll never get to the same place with it. 

You can replicate smartfood cheddar popcorn by tossing your corn with mac and cheese powder, I'd give it a try and see if you get where you want to go, if it still seems wet in comparison then some extra drying may be good.