How to create a framerate independent time delay in Update() without coroutines

I'm creating a turn based board game and trying to create a small pause between the cpu and human player. All my logic is in the Update() function so I can't use coroutines to simulate the pause so I created a method to try delay the time.

 void miniPause ()
     {
         maxPauseTime = Time.realtimeSinceStartup + 2.5f;
         while (Time.realtimeSinceStartup < maxPauseTime) {
             /*
              *Empty loop to create a time delay
              *between the Player && CPU turns
              */
             print ("Time  = " + Time.realtimeSinceStartup);
         }//end loop
     }

 void Update(){
    if(cpu.turn){
    
     miniPause();
     
     //instantiate cpu's piece on the board
      humanPlayer.turn = true;
      cpu.turn = false
    }
    if(humanPlayer.turn){   
       if(Input.Input.GetMouseButtonDown (0)){
         
         //Instantiate human player's piece on the board here
            humanPlayer.turn = false;
            cpu.turn = true
         }
    }
 }

The delay is created alright, problem is everything else pauses as well, like the the board piece stays suspended in mid-air until delay elapses then falls to the board with the cpu's piece.

Is there a way to halt the cpu player without stopping everything else like navmesh motion, particle effects.