CoinsByDistanceExecution.cs

var coinsByDistance = allCoins.OrderBy(Vector3.Distance(transform.position, t.transform.position);
yield return new WaitForSeconds(1f); // Vector3.Distance hasn't called once, everything's still deffered

if (Input.GetKeyDown(KeyCode.A))
{
  foreach (var coin in coinsByDistance) // This iteration makes the LINQ statement execute.
  {
    coin.DoSomething();
  }
}
else
{
  Debug.Log("Player didn't press 'A'... so nothing's causing the LINQ statement to be executed");
}