Implementing internet speed test in Android/IOS application created in unity 2021.3.22f1

Question

I am creating application in unity 2021.3.22f1 (for android and IOS mobiles). I am searching for any options to implement the speed test in the app. I have a hard time finding any paid or free services that let me do api calls from c# to get the speed test details like upload / download. I also tried downloading a hosted file and using stopwatch to calculate the time taken from start to completion and thereby calculating the speed.

I used a file URL to make a web request. the started stopwatch when download progress started and keep checking time taken with amount of data downloaded. This was not giving correct values. Then I tried calculating speed at regular intervals (approximately every 5%) and took the max value ever registered from 0 to 100% download. This seems to have given better values but is still not giving exactly what speed test websites give. part of code I used is given below. I am new to implementing speed test in a mobile application. Any suggestions regarding paid/free API or based on the file download logic below or any other solutions is much appreciated. Also I don't want any option that requires opening a webpage within my application. Thanks in advance

    _request = UnityWebRequest.Get("www.example.com/file1"); //here i used athe file url
        _request.downloadHandler = new DownloadHandlerBuffer();
        Stopwatch stopwatch;

        InitialCallback?.Invoke(_request);
        _request.SendWebRequest();
        UnityEngine.Debug.Log("Web request started");

        while (_request.downloadProgress == 0)
        {
            yield return null;
        }
      
        stopwatch = Stopwatch.StartNew();
        UnityEngine.Debug.Log("Download Started");

        while (_request.downloadProgress < 1)
        {
            yield return null;

            float currentProgress = _request.downloadProgress;
            if (currentProgress >= prevProgress + 0.05f || currentProgress >= 1)
            {
                byte[] dataTemp = _request.downloadHandler.data;
                int currData = dataTemp.Length - prevData;
                long curTime = stopwatch.ElapsedMilliseconds - prevTime;

                float dataInMegaBitsTemp = (currData * 8) / (1000 * 1000);
                float downloadSpeedTemp = (dataInMegaBitsTemp / ((float)curTime / 1000f));

                if (averageSpeed < downloadSpeedTemp)
                {
                    averageSpeed = downloadSpeedTemp;
                }

                prevData = dataTemp.Length;
                prevTime = stopwatch.ElapsedMilliseconds;
                prevProgress = currentProgress;
            }
        }

        stopwatch.Stop();

        UnityEngine.Debug.Log("Download Stopped");
        if (_request.result != UnityWebRequest.Result.Success)
        {
            FailureCallback?.Invoke($"Download failed. \n error: " + _request.error);
            yield break;
        }
        
        UnityEngine.Debug.Log("Speed : " + averageSpeed);