Your component inside the ShellModule is not a standalone component; it exists within the context of the ShellModule.

To use the SidebarComponent in other modules, you need to import the ShellModule in those modules.

It seems like there's some confusion about the concept of exporting components in Angular. When you export a component from a module, it doesn't make the component globally available—it simply allows other modules that import the ShellModule to use that component.