Since I haven't actually read 'maou ni natta node web novel', it's hard to say precisely. However, if we break down the title, 'maou' means 'demon king' in Japanese. 'ni natta' can be translated as 'became' or 'turned into'. 'node' can have various meanings but often implies a reason or a connection. So it might be a story about someone who became a demon king for some reason, and as it's a web novel, it was likely written and shared online, possibly with a large following of fans who are interested in fantasy or isekai - type stories.
I'm not sure specifically as I haven't read it. But generally, 'saikyou no maou' might refer to the'strongest demon king'. So it could be about a character being trained by the strongest demon king in the context of a light novel.
Well, without having read 'boku ga yuusha de maou no boku de light novel', it's hard to say precisely. However, from the title, it seems to imply a story where the main character has a dual nature of a hero and a demon king. This could lead to all sorts of interesting plotlines, like internal struggles between good and evil within the character, or perhaps a story where the hero - demon king has to navigate a world that views these two identities as completely opposed.
I'm not entirely sure as I haven't read this specific light novel. But generally, a light novel often involves unique characters, a fictional world, and a story with various themes such as adventure, friendship or self - discovery. Maybe it's about the journey of Aoi Hikaru on Earth.