Having gotten a look at the print edition of Level 1 Zuikaku, I can confirm it does have a couple of extra chapters going into the immediate aftermath of the final victory, such as the discovery of Zuikaku's state and dealing with the various abyssal ships as they become non hostile, a prologue to chapter 1 showing how mini-Zuikaku came to live with Kaga, as well as an epilogue with purified Shoukaku and Kaga having a talk with mini-Zuikaku about training and growing up. Feels were had, with my rudimentary japanese plus google translate. Hopefully someone who knows what they are doing may scan and translate it in the future.