I think it would make sense to include pudding - it's basically milk with a bit of flour. It's important to include because it shows that there are foods beyond Pancake Local Group that aren't just liquid milk.

One important property of pudding is that unlike pancakes, the space of pudding isn't "chaotic and fractal" because whether you add just enough flour to make it somewhat sticky or so much that you can cut it with a knife, it's still pudding. This means that if we take flour-heavy pudding and somehow add shitload of eggs, we should be able to venture into the Dark Breakfast area. I have a pudding recipe that calls for egg yolks, but I feel like this isn't a good lead. Still it proves further how flexible "pudding" is.

Going back to pancakes, there's one funny variation. "Naleśniki" with cottage cheese and cream (or yoghurt). Cottage cheese and cream are basically milk with extra steps, which means that the entire dish becomes mainly milk. This means that the Pancake Local Group actually stretches much closer to the "milk" vertex than your diagram suggests.

If I were to prepare something that passes as food and sits in the Dark Breakfast Abyss, I'd try scrambled eggs on the thinnest bread I could reasonably make. Something like "scrambled eggs taco".