Totally off topic but does anyone know the name of the manga at the end of chapter 1 ???

If no one replies, maybe try going on their discord and search the mangas they translate. It’s very likely to be one of them.

i’d like to know as well if someone replies

I think it might be part of this book, as in a one shot near the end? The japanese on the image suggests so, it's the same title as this series.

its just an illustration, as far as i know its not an extra