https://pub.dev/packages/proximity_sensor

simple and easy to use flutter plugin package for proximity sensor (only)

In the pubspec.yaml of your flutter project, add the following dependency:

dependencies:
  ...
  proximity_sensor:

In your library add the following import:

import 'package:proximity_sensor/proximity_sensor.dart';

Android 12 and higher are required to specify an explicit value for android:exported
This is an example.

<activity
    android:exported="true"
    ....

(Android only) WAKE_LOCK permission is needed if you run setProximityScreenOff(true) before listening to events

Add below permission in your AndroidManifest.xml file.

<uses-permission android:name="android.permission.WAKE_LOCK"/>

Some recent devices use virtual proximity sensors. There are no physical sensors. I found it hard to trust the sensor information in this case.