The code bellow isn't working on product listing page:
$objectManager = \Magento\Framework\App\ObjectManager::getInstance();
$customerSession = $objectManager->get('Magento\Customer\Model\Session');
echo $customerSession->getCustomer()->getId()."<br/>"; // get
Customer Id
echo $customerSession->getCustomer()->getName()."<br/>"; // get
Full Name
echo $customerSession->getCustomer()->getEmail()."<br/>"; // get
Email Name
echo $customerSession->getCustomer()->getGroupId()."<br/>"; // get
Customer Group Id
Source ref: How to check if customer is logged in or not in magento 2? Any help! appreciated!