app.module.ts

import { BrowserModule } from '@angular/platform-browser';
import { NgModule, Injector } from '@angular/core';
import { createCustomElement } from '@angular/elements';
import { HelloComponent } from './hello/hello.component';

@NgModule({
   declarations: [
      HelloComponent
   ],
   imports: [
      BrowserModule
   ],
   providers: [],
   entryComponents: [HelloComponent]
})
export class AppModule {
    /**
     *
     */
    constructor(private injector: Injector) {
    }

    ngDoBootstrap() {
        const helloComponentEl = createCustomElement(HelloComponent, { injector: this.injector });

        customElements.define('hello', helloComponentEl);
    }
}