magento2-modules/app/code/Wowow/Devis/Block/Adminhtml/Devis.php

<?php

namespace Wowow\Devis\Block\Adminhtml;

class Devis extends \Magento\Backend\Block\Template
{
    
    protected $_template = 'view.phtml';

    public function __construct(
        \Magento\Backend\Block\Template\Context $context, array $data = []
    ) { 
        parent::__construct($context,$data);
    }

    protected function _toHtml() {
        return parent::_toHtml();
    }
    
    public function getCustomer($id)
    {
        $objectManager = $this->getObjectManager();
        $devisModel = $objectManager->create('\Wowow\Devis\Model\Devis');
        $devis = $devisModel->load($id);
        $customerId = $devis->getCustomerId();
        $customerModel = $this->getObjectManager()->create('\Magento\Customer\Model\Customer');
        return $customerModel->load($customerId);
    }
    
    public function getObjectManager()
    {
        return \Magento\Framework\App\ObjectManager::getInstance();
    }
    
    public function getAdresse($id)
    {
        $customer = $this->getCustomer($id);
        return $customer->getAddresses();
    }
    
    public function getCountryHtml($countryCode)
    {
        $objectManager = $this->getObjectManager();
        $countryModel = $objectManager->create('\Magento\Directory\Model\CountryFactory');
        $country = $countryModel->create()->loadByCode($countryCode);
        return $country->getName();
    }
    
}