James Mangold’s Boba Fett movie

Though never officially announced either, there was a time when James Mangold—who’s now directing a fifth Indiana Jones movie—was working on a Boba Fett movie. We aren’t sure how far along that got in development, but it was being kicked around, only to be axed after Solo underperformed and forced a reassessment of the whole “A Star Wars Story” model.
Plus, eventually, fans did get a Boba Fett project, The Book of Boba Fett, which was certainly influenced by the development of many of these projects.