Is it possible to combine multiple small Forge applications, such as two dashboard gadgets, a project page, a global page, and an admin page, into a single app? I would like to have all these small applications together when installing the app, similar to how Tempo works. Could anyone provide a clear example or guidance on achieving this?"
It depends on what you mean by multiple apps. You can have one Forge app that includes all those modules, you just need to add them all to your Forge manifest.