android studio webview how to upload a file?

Question

JavaScript

Question: Why doesn't the selection menu appear when I press the button?
ps I understand that it may be necessary to connect something else in MainActivity.java.
but on the PC version everything is fine ..

MainActivity.java code

package com.example.hello;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.webkit.WebChromeClient;
import android.webkit.WebView;

public class MainActivity extends AppCompatActivity {

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

        WebView web = (WebView)findViewById(R.id.webView);
        web.getSettings().setJavaScriptEnabled(true);
        web.setWebChromeClient(new WebChromeClient());
        web.loadUrl("file:///android_asset/www/index.html");
        web.getSettings().setDomStorageEnabled(true);

        web.getSettings().setDomStorageEnabled(true);
        web.getSettings().setDatabaseEnabled(true);
        web.getSettings().setDatabasePath("/data/data/" + web.getContext().getPackageName() + "/databases/");

    }
}

activity_main.xml code

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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" />
</RelativeLayout>

index.html code

<input type="file" id="img" accept="image/*" onchange="fileupload(this)">

app.js code

function fileupload(input) {
  let file = input.files[0];
  let reader = new FileReader();
  reader.readAsDataURL(file);

  reader.onload = function () {
    localStorage.setItem('img', reader.result);
  }
}

Personally, this is my first time dealing with WebView and in general with Andoid Studio, thanks in advance