Creating an Expo monorepo with Nx involves setting up a workspace using @nx/expo to develop two apps, one for cat facts and another for dog facts, which share branding and components. The process includes creating an Nx workspace, installing necessary tech stacks like React Native Paper for design and @react-navigation for routing, and setting up a shared UI library. The apps are built using EAS (Expo Application Services) to generate binaries for different platforms, with options for local or hosted builds. Submission to app stores requires developer accounts and involves running production builds and using either manual uploads or EAS services for deployment. This approach facilitates scalability and future expansion of the monorepo by allowing reusable libraries and components for additional apps.