app.ts

import {LibModule} from 'lib';

@Component({
  template: '<component-from-sublib></component-from-sublib>',
})
export class AppComponent {

  // Ivy generated:
  static ngComponentDef = defineComponent({
    components: [
      // To know the set of dependencies to list here, we need to
      // know the AppModule selector map. To gather that selector
      // map, we need information from both lib.d.ts and sublib.d.ts,
      // even though sublib.ts is not a direct dependency of app.ts
    ],
    template: function AppComponent_Template(cm) { ... }
  });
}

@NgModule({
  imports: [LibModule]
})
export class AppModule {}

lib.d.ts

import {SublibModule} from './sublib';

export declare class LibModule {
  static ngSelectorMap: SelectorMap<{
    exports: [SublibModule]
  }>;
}

lib.ts

import {SublibModule} from 'sublib';

@NgModule({
  exports: [SublibModule]
})
export class LibModule {}

sublib.d.ts

export declare class SublibComponent {
  // component metadata here
}

export declare class SublibModule {
  static ngSelectorMap: SelectorMap<{
    selectors: [Selector<"component-from-sublib", SublibComponent>]
  }>;
}

sublib.ts

@Component({
  selector: 'component-from-sublib',
  template: '...',
})

@NgModule({
  declarations: [SublibComponent],
})
export class SublibModule {}