With the Pro Max's logic board extracted, we're tempted to say it might be even more compact than the one in the iPhone 12 mini (bottom)—but, the mini's integrated SIM reader also leaves it at an unfair disadvantage.

Here's a quick X-ray view of the board before we slice it open. We'll have to take it one layer at a time, but it's neat to see them all at once. It's an amazingly intricate city of silicon driving these iPhones.