This is a functioning AndroidManifest.xml for linking via a local url scheme. In this case appname:// with any (*) following path

To test this you have to redirect to it. Chromium at this time does not understand or process app url schemes. So a 302 redirect from a trusted publicly available url is the best method for testing.

Note how the second intent-filter here is still inside the .MainActivity <activity>

Different categories and an additional <data> tag are used.

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.appname">

    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> 
    <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/>

    <application
      android:name=".MainApplication"
      android:label="@string/app_name"
      android:icon="@mipmap/ic_launcher"
      android:allowBackup="false"
      android:theme="@style/AppTheme">
      <activity
        android:name=".MainActivity"
        android:label="@string/app_name"
        android:configChanges="keyboard|keyboardHidden|orientation|screenSize"
        android:windowSoftInputMode="adjustResize">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <action android:name="android.intent.action.DOWNLOAD_COMPLETE"/>
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
          <intent-filter android:label="@string/app_name">
              <action android:name="android.intent.action.VIEW" />
              <category android:name="android.intent.category.DEFAULT" />
              <category android:name="android.intent.category.BROWSABLE" />
              <data android:scheme="appname" android:host="*" />
          </intent-filter>
      </activity>
      <activity android:name="com.facebook.react.devsupport.DevSettingsActivity" />
    </application>

</manifest>