Creating module PHPCodez_Customattribute to add a new attribute to list all the customer groups including ‘NOT LOGGED IN’.

1) Declare the module

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
<module name="PHPCodez_Customattribute" setup_version="0.0.1" />
</config>

2) Register the module.

<?php
\Magento\Framework\Component\ComponentRegistrar::register(
\Magento\Framework\Component\ComponentRegistrar::MODULE,
'PHPCodez_Customattribute',
__DIR__
);

3) Create Install script.

<?php
namespace PHPCodez\Customattribute\Setup;

use Magento\Eav\Setup\EavSetup;
use Magento\Eav\Setup\EavSetupFactory;
use Magento\Framework\Setup\InstallDataInterface;
use Magento\Framework\Setup\ModuleContextInterface;
use Magento\Framework\Setup\ModuleDataSetupInterface;

class installData implements InstallDataInterface {
private $eavSetupFactory;
protected $logger;

public function __construct(EavSetupFactory $eavSetupFactory,\Psr\Log\LoggerInterface $logger) {
$this->eavSetupFactory = $eavSetupFactory;
$this->logger = $logger;
}

public function install(ModuleDataSetupInterface $setup, ModuleContextInterface $context) {
$this->logger->info("System - upgrading module - Creating product attribute - product_customer_group");

$eavSetup = $this->eavSetupFactory->create(['setup' => $setup]);
$eavSetup->addAttribute(
\Magento\Catalog\Model\Product::ENTITY,
'product_customer_group',[
'type' => 'text',
'backend' => 'Magento\Eav\Model\Entity\Attribute\Backend\ArrayBackend',
'frontend' => '',
'label' => 'Hide Product For',
'input' => 'multiselect',
'class' => '',
'source' => 'PHPCodez\Customattribute\Model\Config\Source\Group\Multiselect',
'global' => \Magento\Eav\Model\Entity\Attribute\ScopedAttributeInterface::SCOPE_GLOBAL,
'visible' => true,
'required' => true,
'user_defined' => false,
'default' => '',
'searchable' => false,
'filterable' => false,
'comparable' => false,
'visible_on_front' => false,
'used_in_product_listing' => true,
'unique' => false,
'apply_to' => ''
]
);
}
}

4) Create source model.

<?php
namespace PHPCodez\Customattribute\Model\Config\Source\Group;
use \Magento\Customer\Model\ResourceModel\Group\Collection;

class Multiselect extends \Magento\Eav\Model\Entity\Attribute\Source\AbstractSource implements \Magento\Framework\Option\ArrayInterface {

protected $_customerGroup;

protected $_options;

public function __construct( Collection $customerGroup ) {
$this->_customerGroup = $customerGroup; 
}

public function toOptionArray() {
if (!$this->_options) {
$this->_options = $this->_customerGroup->toOptionArray();
}
return $this->_options;
}

public function getAllOptions() {

if (!$this->_options) {
$this->_options = $this->_customerGroup->toOptionArray();
}
return $this->_options;
}
}


5) Run the following commands

$ php bin/magento indexer:reindex
$ php bin/magento setup:upgrade
$ php bin/magento setup:di:compile
$ php bin/magento setup:static-content:deploy -f
$ php bin/magento cache:flush