You will have to migrate
Technically speaking it is it's own version of magento
If you don't want to immediately deal with adobe you could try an agency. They will give you much more of an idea on cost.
Below is the code which useful to get store credit..
require __DIR__ . '/app/bootstrap.php';
$bootstrap = Bootstrap::create(BP, $_SERVER);
$objectManager = $bootstrap->getObjectManager();
$instance = \Magento\Framework\App\ObjectManager::getInstance();
$state = $objectManager->get('\...