Part 2 of the script to place holograms based on raycasts with AR Foundation

ARPlaceHologram.cs

void Update()
{
    // Only consider single-finger touches that are beginning
    Touch touch; 
    if (Input.touchCount < 1 || (touch = Input.GetTouch(0)).phase != TouchPhase.Began) { return; }
        
    // Perform AR raycast to any kind of trackable
    if (_raycastManager.Raycast(touch.position, Hits, TrackableType.AllTypes))
    {
        // Raycast hits are sorted by distance, so the first one will be the closest hit.
        var hitPose = Hits[0].pose;

        // Instantiate the prefab at the given position
        // Note: the object is not anchored yet!
        Instantiate(_prefabToPlace, hitPose.position, hitPose.rotation);

        // Debug output what we actually hit
        Debug.Log($"Instantiated on: {Hits[0].hitType}");
    }
}