How to be notified of new GamObject creation?

There are a couple of ways to acheive this but in answer to your question no i don't think unity has a pre-existing method to do so Below is an example of using an instantiation to fire a function to message the Debug menu.

     GameObject curSpawn;
     GameObject spawn;
     bool noNotice;
     
     
     void Start() {
       GameObject sp = GameObject.Instantiate (spawn, transform.position, transform.rotation);
     curSpawn = sp;
     noNotice = true;
     }
     
     void Update(){
        if(noNotice && curSpawn != null) {
              GetNotice();
     }
     }
     void GetNotice() {
            Debug.Log(curSpawn.name + " has been spawned");
     }
 

let me know if this helps you, if not i'll make some changes.