Last month we spent a week at the Boardwalk and we walked over to the Hess Station for a few needs. I took a bunch of pictures and notes of what they have for selection. I hope this helps someone!
WDW only has Chase ATMs, this might be useful for someone to avoid a charge...
Lots of random stuff. You could make spaghetti (without meat), Mac & Cheese and PB&J...wait, they were out of peanut butter. You could make jelly sandwiches.

Or Spam ones.
You might have spied the coffee. The 8-12 type filters are the ones you use in a
DVC Villa, but for the regular hotel rooms you need the 4 cup ones.
Some single-size cereals and full box too.
I know this matters to a lot of people!
Trail mix type stuff on the end.
Only Coke products. And no, they don't sell gum!
Handy stuff!
The only fruit in the entire joint.
Single-serving type and 1/2 Gallons.
Half & Half
Overall, here is what I put in my notes: Hess is a lot smaller than I had imagined. They have a LOT of various chips and a few "healthy" choices like pita and veggies chips. The only fruit they had were bananas that were still green and Red Delicious apples. Boring. No veggies, not even a bag of baby carrots. They sold hot dog buns, but no hot dogs. No string cheese or cups of yogurt. 1/2 gallon of milk was $3.09, it's $0.15 cheaper at the Boardwalk, which was surprising. Soda was on sale, and the worker told me about that, so I got 2-12 packs for just over the price of one. A gallon of water is $1.99. A few toiletry items, feminine products, diapers, wipes, toilet paper, tooth care, hair stuff. Candy bars and other candy-typical gas stations stuff. There was a section for hot food, but the displays were empty while I was in there. One was for hot breakfast sandwiches. There was a coffee bar area too, and they did have a roller cooker of hot dogs. The only juice they had was single-serving style. A lot of things didn't have price tags.
It was kinda strange to see the CM's...in costume...pumping gas and purchasing items!