Midway is very walkable, though there's a good bit of traffic so the surrounding areas aren't the nicest place to walk, but there are exits and sidewalks.
You might exit directly from the terminal onto Cicero, but there are few options where you could both wait comfortably in case of rain or snow or where a car could safely stop out of traffic.
A good option is to follow the signs to the CTA Station "Trains to City / Trains to Loop" (straight ahead as you exit the terminal, don't forget to go downstairs right after you exit the secure area to get your check luggage, if any).
At the Midway CTA station you can exit to the bus boarding area, you can cross it to this parking lot (41.7852416,-87.7399196) that doesn't have controlled access. This location is just down the street from the Chill With Us Yogurt Cafe but saves you having to cross the road.