Allow notifications Android webview

Context I'm trying to add push notifications that come from my website. My code:

• MainActivity.java

package com.example.neurofinance;

import androidx.appcompat.app.AppCompatActivity;

import android.annotation.TargetApi;
import android.content.Context;
import android.net.http.SslError;
import android.os.Build;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.webkit.JavascriptInterface;
import android.webkit.SslErrorHandler;
import android.webkit.WebResourceRequest;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Toast;



public class MainActivity extends AppCompatActivity {

    public class WebAppInterface {
        Context mContext;

        /** Instantiate the interface and set the context */
        WebAppInterface(Context c) {
            mContext = c;
        }

        /** Show a toast from the web page */
        @JavascriptInterface
        public void showToast(String toast) {
            Toast.makeText(mContext, toast, Toast.LENGTH_SHORT).show();
        }
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        return true;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        this.getWindow().getDecorView().setSystemUiVisibility(

                View.SYSTEM_UI_FLAG_LAYOUT_STABLE

                        | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION

                        | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN

                        | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION

                        | View.SYSTEM_UI_FLAG_FULLSCREEN);



        WebView webView = findViewById(R.id.webView);
        webView.addJavascriptInterface(new WebAppInterface(this), "Android");
        
        webView.getSettings().setDomStorageEnabled(true);

        webView.getSettings().setJavaScriptEnabled(true);



        webView.getSettings().setUseWideViewPort(true);//setting wide view
        webView.getSettings().setLoadWithOverviewMode(true);//setting default zoomed out view
        webView.setInitialScale(1);
        webView.getSettings().setBuiltInZoomControls(true);//setting zoom controls

        webView.loadUrl("https://neurofinance.rf.gd/");
        

        WebViewClient webViewClient = new WebViewClient() {

            @SuppressWarnings("deprecation") @Override

            public boolean shouldOverrideUrlLoading(WebView view, String url) {

                view.loadUrl(url);

                return true;

            }

            @Override
            public void onReceivedSslError (WebView view, SslErrorHandler handler, SslError error) {
                handler.proceed();
            }

            @TargetApi(Build.VERSION_CODES.N) @Override

            public boolean shouldOverrideUrlLoading(WebView view, WebResourceRequest request) {

                view.loadUrl(request.getUrl().toString());

                return true;

            }
        };

        webView.setWebViewClient(webViewClient);

        if (Build.VERSION.SDK_INT >= 21)
            webView.getSettings().setMixedContentMode( WebSettings.MIXED_CONTENT_ALWAYS_ALLOW );
    }
}

• AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.neurofinance">
    <uses-permission android:name="android.permission.INTERNET"/>
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity"
            android:configChanges="orientation|keyboardHidden|screenSize">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

• activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <WebView
        android:id="@+id/webView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        />

</androidx.constraintlayout.widget.ConstraintLayout>

Problem
I tried code from this post but it did not help.

However, I think that I should allow notifications somewhere. I tried to open my website in a browser and it actually asks the permission while my app does not. (left: browser, right: webview)

from Allow notifications Android webview