You can just make it on the stovetop in a pot with a top

Air poppers can be small, mine is about ten inches tall, five inches wide and deep. I'm no fan of single use appliances but it makes a healthy snack so easy (just pour half a cup of kernels in and switch it on) that it gets a pass. It's fast too, takes about a minute and can't burn them. The only cleaning it needs it to shake out any popcorn bits that for some reason didn't get ejected. It was a great value purchase for seven bucks.

The downside is it's loud AF.

Just any pot works, you dont need a machine.

I use spoonful of coconut oil or clarified butter, but coconut oil works better. Heat oil

put corn kernels, i put just to cover bottom of the pot, or a bit less.

Then you cover and shake.

Use fine salt and fine msg for seasoning. I like adding smoked paprika powder.

I have a collapsible silicone bucket with a lid for popcorn making that goes into the microwave. It's easy to use, doesn't require any fat, also serves as a bowl and you can just throw it into the dishwasher. Size-wise, it's probably not that different from an air popper when collapsed, but it's easier to find a spot for; mine is on top of the stack of roughly bowl-shaped things. And you could also use it as a bowl for other things, so it's not necessarily single-purpose.

Stove top popcorn is too stupidly easy to buy a one off gadget. I make popcorn on the stove at least 3 times a week just using vegetable oil and flavacol. My wife and I are now spoiled on this popcorn.

You can take the plain popcorn and pop it in a microwave in a brown paper lunch sack that is folded over. No need for a one off machine.

I've been using nutritional yeast and it is like a cheese dust replacement. Would not recommend eating it by itself though (ie what's leftover at the bottom of the bowl).

So a double whammy for health. To OP: Do an internet search for volume eating - lots of good suggestions there.