Ionic 5 Capacitor: Push Notification register UserGroup to firebase server/console?

I made the push notifications according to the Capacitor instructions. Below is the code for this.

But how can I specify the device to a user group in firebase, so that a device is assigned to a user group and I can therefore choose between the user groups when placing a push notification? How can this approach be used to assign a device to a user group in firebase?

import { Component, OnInit } from '@angular/core';

import {
  Plugins,
  PushNotification,
  PushNotificationToken,
  PushNotificationActionPerformed } from '@capacitor/core';

const { PushNotifications } = Plugins;

@Component({
  selector: 'app-home',
  templateUrl: 'home.page.html',
  styleUrls: ['home.page.scss'],
})

export class HomePage implements OnInit {

  ngOnInit() {
    console.log('Initializing HomePage');

    PushNotifications.register();

    PushNotifications.addListener('registration', 
      (token: PushNotificationToken) => {
        alert('Push registration success, token: ' + token.value);
      }
    );

    PushNotifications.addListener('registrationError', 
      (error: any) => {
        alert('Error on registration: ' + JSON.stringify(error));
      }
    );

    PushNotifications.addListener('pushNotificationReceived', 
      (notification: PushNotification) => {
        alert('Push received: ' + JSON.stringify(notification));
      }
    );

    PushNotifications.addListener('pushNotificationActionPerformed', 
      (notification: PushNotificationActionPerformed) => {
        alert('Push action performed: ' + JSON.stringify(notification));
      }
    );
}