PlumberUltimateAds/Assets/Scripts/NotificationPermissionRequester.cs

using UnityEngine;

public class NotificationPermissionRequester : MonoBehaviour
{
    void Start()
    {
#if UNITY_ANDROID && !UNITY_EDITOR
        using (AndroidJavaClass version = new AndroidJavaClass("android.os.Build$VERSION"))
        {
            int sdkInt = version.GetStatic<int>("SDK_INT");

            if (sdkInt >= 33)
            {
                using (AndroidJavaClass unityPlayer = new AndroidJavaClass("com.unity3d.player.UnityPlayer"))
                using (AndroidJavaObject activity = unityPlayer.GetStatic<AndroidJavaObject>("currentActivity"))
                {
                    string permission = "android.permission.POST_NOTIFICATIONS";

                    using (AndroidJavaClass permissionChecker = new AndroidJavaClass("androidx.core.content.ContextCompat"))
                    {
                        int permissionStatus = permissionChecker.CallStatic<int>("checkSelfPermission", activity, permission);

                        if (permissionStatus != 0) // not granted
                        {
                            string[] permissions = new string[] { permission };
                            using (AndroidJavaClass activityCompat = new AndroidJavaClass("androidx.core.app.ActivityCompat"))
                            {
                                activityCompat.CallStatic("requestPermissions", activity, permissions, 0);
                            }
                        }
                    }
                }
            }
        }
#endif
    }
}