class EcsComponentPool<T> : IEcsComponentPool where T : class, new () 
{
	public static readonly EcsComponentPool<T> Instance = new EcsComponentPool<T> ();
	private Func<T> _factory;
	
	public void MapFactory(Func<T> factory)
	{
		_factory = factory;
	}
	
	public int GetIndex () {
		... всякая мишура
		...
		
		T item;
		if(_factory != null)
		{
			item = _factory();
		}
		else
		{
			item = new T();
		}
		Items[_itemsCount++] = item;
		
		return id;
	}
}

...

public class SomeInitializeSystem
{
	public void Initialize()
	{
		EcsComponentPool<MySuperComponent>.Instance.MapFactory(() => new MySuperComponent());
	}
}