Passing Func event as parametar

Hi this is more a C# question but might be useful to people using unity. I am writing the countdown script that is going to be used like this:

 //simple countdown duration:10s, when done call OnFinish
 this.gameObject.AddComponent<Countdown>().StartCountdown(10,OnFinished);
 //overloaded, countdown duration:10s when done call OnFinish, report in 1s call OnProgress
 this.gameObject.AddComponent<Countdown>().StartCountdown(10,OnFinished,1,OnProgress);

countdown script is attached to the GO that needs countdown and destroys itself when done. I managed to use simple Action event for OnFinish and OnProgress but i could not get the Func to work since i want to return some values to the script that uses the countdown.

here is the current countdown script, help me expand this and learn along the way! thanks!

 using UnityEngine;
 using System;
 using System.Collections;
 
 public class Countdown : MonoBehaviour {
 
     float startTime;
     float elapsedTime;
     
     event Action Finished;
     event Action Progress;
     int progressCount;
     
     public void StartCountdown(int seconds, Action OnFinished)
     {
         Finished += OnFinished;
         StartCoroutine(Count(seconds));
     }
     
     public void StartCountdown(int seconds, Action OnFinished, int progress, Action OnProgress)
     {
         Finished += OnFinished;
         Progress += OnProgress;
         progressCount = (int)(seconds / progress);
         StartCoroutine(CountWithProgress(seconds,progress));
     }
     
     IEnumerator Count(int duration)
     {
         startTime = Time.time;
         
         while(elapsedTime < duration)
         {
             elapsedTime = startTime + Time.time;
             yield return null;
         }
         
         if(Finished != null)
             Finished();
         
         Destroy(this);
     }
     
     IEnumerator CountWithProgress(int duration, int progress)
     {
         int i = 1;
         startTime = Time.time;
         
         while(elapsedTime < duration)
         {
             elapsedTime = startTime + Time.time;
             
             if(elapsedTime > progress * i)
             {
                 if(Progress != null)
                     Progress();
                 
                 i++;
             }
             
             yield return null;
         }
         
         if(Finished != null)
             Finished();
         
         Destroy(this);
     }
 }