When playing Greed mode, items that are available only in the normal game will still not appear despite Chaos; the modes' different item pools stay separate.
As the item does not mix or combine item pools, it is possible to deplete smaller item pools and end up with Breakfast before all items in the game have been taken.
Thus, if Chaos tries to pull from an item pool that is already depleted, it will not pull from a different pool and instead give you Breakfast.
As many Greed mode item pools are small, Chaos tends to result in Breakfast more often during Greed mode.
Since all item pools have the same probability of being selected, bomb-related items are much more common due to the Bomb Bum item pool.
Each pool has a weight based on the number of items in the pool. Items from large pools such as Treasure Room, Shop, and Boss are very likely, while items from small pools like Bomb Bum and Planetarium are more rare.
If an item outside of the Devil Room pool appears as a Devil deal, it will always cost 1 Red Heart container (or 3 Soul Hearts should Isaac have no Red Hearts).