Pairing custom meta field with NOV in Uni CPO

functions.php

add_action( 'woocommerce_product_options_pricing', 'uni_display_fields' );
add_action( 'woocommerce_process_product_meta', 'uni_save_fields' );

function uni_display_fields() {
	woocommerce_wp_text_input(
		array(
			'id'          => 'uni_paired_meta',
			'label'       => 'Meta field paired with NOV',
			'description' => 'This value will be used instead of {uni_nov_cpo_paired_meta}',
		)
	);
}

function uni_save_fields( $post_id ) {
	$product = wc_get_product( $post_id );
	$product->update_meta_data( 'uni_paired_meta', sanitize_text_field( $_POST['uni_paired_meta'] ) );
	$product->save();
}

add_filter('uni_cpo_nov_variable_value', 'uni_paired_nov_value', 10, 4);

function uni_paired_nov_value($value, $product, $variables, $slug) {
	if ('paired_meta' === $slug && function_exists('uni_cpo_calculate_formula')) {
		$val = get_post_meta($product['id'], 'uni_paired_meta', true);
		return uni_cpo_calculate_formula($val);
	}

	return $value;
}

thanks