Migrate Users from Joomla 3 to Joomla 4 with same UserIds and Passwords

Question

So I successfully migrated users from a Joomla 3 database into a Joomla 4 database. I am hoping there is a nicer way if anyone has done it.

In particular, I couldn't work out how to create a user using the UserModel with a specific Id. Hence I had to set the user table autoincrement in the database to a high number to avoid collisions for when I set them back.

I get the impression that using the UserModel here is completely redundant and this would be better as a raw sql insert - but the question is... is there a good way to programmatically create users with known ids and password hashes.

$options = [
    'host'  => 'localhost',
    'database' => 'xxxxxxxxxxxx',
    'password' => 'xxxxxxxxxxxx',
    'user' => 'xxxxxxxxxxxxxxx',
    'prefix' => 'xxxxxx_',
];

// Connect to Old Joomla 3 Database

$odb = (new DatabaseFactory)->getDriver('mysqli', $options);
   
$query = $odb->getQuery(true);
$query->select('*');
$query->from('#__users');
$query->order('id');
$odb->setQuery($query);
$existing_users = $odb->loadAssocList('username');

$MvcFactory = $app->bootComponent('com_users')->getMVCFactory();

foreach($existing_users as $data){

    // Start everyone as Registered
    $data['groups'] = [2];

    unset($data["id"]);
    unset($data["lastResetTime"]);
    unset($data["resetCount"]);
    unset($data["otpKey"]);
    unset($data["otep"]);
    unset($data["requireReset"]);
    unset($data["authProvider"]);
    unset($data["params"]);

    // This needs to be an array so either json_decode old value or set blank
    $data["params"] = [];

    // empty date should be NULL in these times
    if($data["lastvisitDate"] == "0000-00-00 00:00:00"){
        unset($data["lastvisitDate"]);
    }

    $userModel = $MvcFactory->createModel('User', 'Administrator', ['ignore_request' => true]);

    // This will make a new id and hash the old hashed password
    if (!$userModel->save($data)){
        throw new Exception($userModel->getError());
    }
}

// Now Set all the Ids and Passwords back as they were
$db = JFactory::getDbo();
$query = $db->getQuery(true);
$query->select('id,username');
$query->from('#__users');
$db->setQuery($query);
$users = $db->loadAssocList();

foreach($users as $u){

    // Skip any New Joomla 4 Users
    if(empty($existing_users[$u['username']])){continue;}

    $sql = 'UPDATE `#__users` SET `id` = ' . $existing_users[$u['username']]['id'] . ', `password` = "' . $existing_users[$u['username']]['password'] . '" WHERE `id` = ' . $u['id'];
    $sql2 = 'UPDATE `#__user_usergroup_map` SET `user_id` = ' . $existing_users[$u['username']]['id'] . ' WHERE `user_id` = ' . $u['id'];

    $db->setQuery($sql);
    $db->execute();
    $db->setQuery($sql2);
    $db->execute();

}