It seems I have reading problem, I’ve already opened the menu before asking sending this question.
What is the recomended way if I want to modify <nav></nav> structure? add some icons, add other html tag, etc, something that is not accomodate by the customizer menu?
The theme has many action hooks that are exposed in Elemeents.
Example: generate_menu_bar_items is where the search icon and other icons get hooked into the desktop and mobile navs.
In addition to this there are many other hooks, check the hook list in either element to see them all listed under Navigation.
If theres a specific place you need then let me know