An alternative is to create a server on another device on your local network that the old iPad can connect to by HTTP and transfer the photos via Safari. For example, use FTPManager (
https://apps.apple.com/us/app/ftpmanager-ftp-sftp-client/id5...) on a newer iOS device to create the server.
You may also be able to do the reverse (create the server on your old iPad) if that’s easier. FTPManager says it works on iOS 9.