Fetch ID of object I just made and send to the database PHP Mysql

Question

So here I made an object that's getting saved in my database. In the database another table row is made with an ID.

<?php
        if(isset($_POST['verzenden'])) {
            $required = array('fname', 'lname', 'email', 'adress', 'zipcode');
            $error = false;
            foreach($required as $field) {
                if (empty($_POST[$field])) {
                    $error = true;
                }
            }
            if ($error) {
                echo "<div class='text-danger'>*All fields are required.</div>";
            } else {
                saveCustomer($_POST['fname'],$_POST['lname'],$_POST['email'],$_POST['adress'],$_POST['zipcode']);
                header("Location: sushi.php");
            }
        }
        ?>

Here is the function for it:

function saveCustomer(string $fname, string $lname, string $email, string $adress, string $zipcode): void
{
    global $pdo;

    $sth = $pdo->prepare('INSERT INTO customer (fname, lname, email, adress, zipcode) VALUES (:f,:l,:e,:a,:z)');
    $sth->bindParam("f", $fname);
    $sth->bindParam("l", $lname);
    $sth->bindParam("e", $email);
    $sth->bindParam("a", $adress);
    $sth->bindParam("z", $zipcode);
    $sth->execute();
}

Database picture

How can I fetch the user's ID I just made using this function so I can put it in a SESSION?

function getCustomer():array
{
    global $pdo;
    $sth = $pdo->prepare('SELECT * FROM customer order by date DESC');
    $sth->execute();
    return $sth->fetchAll(PDO::FETCH_CLASS, 'Customer');
}