Although the movie is titled "Love, Simon" it is actually an adaptation of the book "Simon vs The Homosapiens Agenda." The movie originally had the same name as the book, but it was too long to say, hence the name change.
The trivia item below may give away important plot points.
The last cast member to be announced was Blue. Book fans spent months waiting to discover the actor who would be playing Simons email buddy. Throughout the whole of filming, no pictures were released of the actor.