How do I display simple products in a custom product, even if they are not in stock?

I need to display options on the detailed page of a custom product, even if no simple product that is associated with the custom product is available. I suggest https://magecomp.com/blog/show-out-of-stock-for-configurable-products-magento-2 / this is Magento 2.2 How to show out of stock in configurable product a reference. Magento v 2.4.2.

It is very strange to me that the system does not even try to call the code below if all items are out of stock

    <?php
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
?>

<?php
/** @var $block MagentoConfigurableProductBlockProductViewTypeConfigurable*/
$_product    = $block->getProduct();
$_attributes = $block->decorateArray($block->getAllowAttributes());
?>
<?php if ($_product->isSaleable() && count($_attributes)) :?>
    <?php foreach ($_attributes as $_attribute) : ?>
        <div class="field configurable required">
            <label class="label" for="attribute<?= $block->escapeHtmlAttr($_attribute->getAttributeId()) ?>">
                <span><?= $block->escapeHtml($_attribute->getProductAttribute()->getStoreLabel()) ?></span>
            </label>
            <div class="control">
                <select name="super_attribute[<?= $block->escapeHtmlAttr($_attribute->getAttributeId()) ?>]"
                        data-selector="super_attribute[<?= $block->escapeHtmlAttr($_attribute->getAttributeId()) ?>]"
                        data-validate="{required:true}"
                        id="attribute<?= $block->escapeHtmlAttr($_attribute->getAttributeId()) ?>"
                        class="super-attribute-select">
                    <option value=""><?= $block->escapeHtml(__('Choose an Option...')) ?></option>
                </select>
            </div>
        </div>
    <?php endforeach; ?>
    <script type="text/x-magento-init">
        {
            "#product_addtocart_form": {
                "configurable": {
                    "spConfig": <?= /* @noEscape */ $block->getJsonConfig() ?>,
                    "gallerySwitchStrategy": "<?= $block->escapeJs($block->getVar(
                        'gallery_switch_strategy',
                        'Magento_ConfigurableProduct'
                    ) ?: 'replace'); ?>"
                }
            },
            "*" : {
                "Magento_ConfigurableProduct/js/catalog-add-to-cart": {}
            }
        }
    </script>
<?php endif;?>