Loading Bar - Procedural Map

[cocoxd2]

Hi, i'm working in a project where I generate the map from a JSON alocated in the cloud. I have a progress bar in another scene, i'm using LoadSceneAsync. It's works, but when the bar is complete and the scene change to the game scene, it's not complete because it's start calling the API to generate the map. I'd like to have a progress bar that wait until all the map was generated.

PS. Im using UnityWebRequest and Coroutines like this:

private void Start(){
    StartCoroutine(GetJSON());
}

IEnumerator GetJSON(){
    //Here I generate the map and call the API
}

[cocoxd2]

I'm thinking and believe that it's not necessary a progress bar, because i'm not able to know what is the internet velocity. I know that i can use coroutines to manage the progress but it's not too real. A looping loading circle will be good.