Haven’t stayed there myself, but I would assume they have a mini fridge at best. No real freezer. There are usually multiple shelves. You could fit some water bottles laying down and some water bottles in the door. Not sure how that translates to milk. Maybe 1/2 gal could fit laying down?
A half gallon will fit laying down. It also fits upright if you remove a shelf. Not sure I’ve ever seen a 4 gallon container of milk. Did you mean 4 quarts (same as 1 gallon)?
No freezer section in the new fridges at Pop, unfortunately.
A gallon is 3.8 liters. Most large soda pop bottles sold in the U.S.A. are 2.0 L. That's about the equivalent of a half gallon (well just this much smaller), which should fit fine in one of the fridges, standing up, if the shelf is removed.
The bottle is about the size of a half gallon of milk. The old fridges were bigger and could handle gallon milks. I am not a fan of these smaller fridges, no way will a togo box fit in them, they are not deep enough.