Is there a way to add a condition to know if the current item of the navigation walker is the last child of the menu or parent?

| Item 1      | Item 2      |
| - Item 1.1  | - Item 2.1  |
| - Item 1.2  | - Item 2.2  |
| - Item 1.3  |<----------------- Determine if current item is last child 

For example:

if ($item->last_child(of_current_parent) {
   ...
}

So, how do you determine if the current item is the last child of its siblings?

EDIT: Solved my problem trying this: https://wordpress.stackexchange.com/a/49005/91164
But had to change the logic quite a bit to fit my needs. See my answer below.