Just a head's up, I don't think there's a need for a gallery save. I just talked to the pig in the gallery and I got an option to unlock everything. I don't know if you have to do something to receive that, but I had only unlocked maybe half of them, not even that, when the pig gave the option.
Beyond that, just to clarify the ending, it wasn't the enemy nation saving them. The war was faked from the beginning to make money. There was a group that broke off from the two nations that want to expose that or something. I don't know. It wasn't really explained well at all. Not denying that. I just wanted to mention that part.
Also, the black market salesman does give an item that lets you buy the costumes for free along with giving more blueprints. Is there supposed to be a new game+ or something? Beating it also gives a message about three new scenes, but they must already be unlocked by the pig.
It was definitely abrupt and I feel like there's still things missing like being able to get some of these scenes in the gallery through the actual game and the aforementioned unlocking of the costumes. I don't know. Beats me.