Iconic Delivery slots (WDS) define specific for a category

funcitons.php

<?php

/**
 * Iconic WDS - Set specific dates for a product category.
 *
 * @param array $dates
 * @param string $format
 * @param bool $ignore_slots
 *
 * @return array
 */
function iconic_wds_modify_bookable_dates( $dates, $format, $ignore_slots ) {
	// @todo replace 'christmas-pack' with your category.
	if ( ! iconic_check_for_cart_item_in_category( 'christmas-pack' ) || 'array' === $format ) {
		return $dates;
	}

	$modified_dates = array(
		'12/15/2022',
		'12/16/2022',
		'12/17/2022',
		'12/18/2022',
		'12/19/2022',
		'12/20/2022',
		'12/21/2022',
		'12/22/2022',
		'12/23/2022',
	);

	foreach ( $modified_dates as $date ) {
		$available_dates[] = date_i18n( $format, strtotime( $date ) );
	}

	return $available_dates;
}
add_filter( 'iconic_wds_available_dates', 'iconic_wds_modify_bookable_dates', 10, 3 );

/**
 * Check cart for product in category.
 *  * @param array $categories Categories.
 *  * @return bool
 */
function iconic_check_for_cart_item_in_category( $categories = array() ) {
	if ( empty( $categories ) ) {
		return false;
	}

	// Set our flag to be false until we find a product in that category.
	$has_item = false;

	// Check each cart item for our category.
	foreach ( WC()->cart->get_cart() as $cart_item_key => $cart_item ) {
		$product = $cart_item['data'];

		if ( has_term( $categories, 'product_cat', $product->get_id() ) ) {
			$has_item = true;

			// Break because we only need one "true" to matter here.
			break;
		}
	}

	return $has_item;
}