From your updated question : It seems that all you want to do is to "print" the selectected available country based on your backend configuration.
All backend configurations are saved in the database in the table
core_config_data so all you have to do it get it from there using scope config.
I haven't check more than that but I suspect that the good path is
This is where you defined your allowed countries from your backend.
On the Admin sidebar, go to Stores > Settings > Configuration.
In the left panel under General, choose General.
Expand Expansion selector the Country Options section.
Choose the Default Country where your business is located.
In the Allow Countries list, select each country from which you accept orders.
To get the list; you can call this from your block into your template
public function __construct(
/* Add below dependencies */
$this->allowedCountryModel = $allowedCountryModel;
//Call the below function to fetch countires
Cf : https://magento.stackexchange.com/a/200368/89569