Partially. The core idea and some elements of Juno draw from real experiences, but it's not a completely factual account. The filmmakers took creative liberties to shape the story for the screen.
The movie Juno is not based on a true story. It was written as an original fictional narrative to entertain and engage audiences with its unique plot and characters.
One possible plot could be exploring Juno's relationship with the baby's father during the pregnancy. Maybe they face more challenges or grow closer as they anticipate the arrival of the baby.
There might be a fanfiction where Starkiller and Juno have a falling out over a mission decision. But then they realize they need each other and reconcile in a very emotional way. It could explore their complex relationship deeper.
I'm not sure specifically as I haven't read it directly. It could be a story about Juno's experiences in a street while reading, perhaps encountering various people or events that are dear to Juno.
Finding 'Juno' pregnant fanfiction might be a bit tricky. Some fanfiction communities on Reddit might be able to point you in the right direction. You could post a request there asking if anyone knows of any good 'Juno' pregnant fanfiction. Just make sure to follow the community rules.
Long stories can explore deep themes more thoroughly. In '1984', George Orwell takes time to build up the dystopian world and fully explore ideas like totalitarianism, surveillance, and the loss of individuality. They can also capture different aspects of a time period or culture in great detail, like 'One Hundred Years of Solitude' does for the fictional town of Macondo and Latin American culture.