There will be sneaking.
if I were cardboard I'd totally flat Stanley that stuff and squeeze in between some boxes. It'd be a creative use of the visual style to incorporate some slapstick flat jokes like paper Mario does
I'm really critical of games so you can take what I say with a grain of salt, but a thematic choice such as the games cardboard aesthetic could totally find it's way into the mechanics and writing, and it probably should. The part where D basically folds Into the chair and swivels around is a really subtle touch and I like stuff like that. But you could totally get even more creative with the cardboard. Like a link between words esque wall platformer segment or stealth that allows you to shimmy In between tight cracks to avoid detection. It doesn't have to exist but it seems like a big missed opportunity and makes the visual style seem more like an arbitrary design choice than an important part of the game.
This is just stuff I like to see. I'm sure your boys and gals down at minilith are making some good calls anyways