I have to admit that this reference photo was too difficult for me. I have absolutely no way of accurately identifying the position of the muscles. I accomplished this by relying on the junction of the deltoid and trapezius to guess where the scapula is located.

I slightly modified the angle of the character's rib cage to create a more dramatic effect. However, something seems to be missing on the left side, between the pelvis and the rib cage.

I know there's still rhomboid here, but wouldn't the gap between this scapula and the erector spinae be a bit large?

I'm trying to understand the part where the external obliques and the serratus anterior overlap each other, is this correct?

No so sure about the serratus anterior and the obliques part, please check.