Xiaomi must have changed it recently. At the time i wrote this post, the Mi App was not able to recognize the Homekit Aqara hub. Now it shows it in the list. I got aware of this a few days ago as well.
But i think it is still not possible to enable LAN funcions and get the key of it.
Look here https://community.aqara.com/forum/faq-1/topic/how-to-connect-the-aqara-hub-to-the-network-78 and scroll down to the questions of Didier3L. An Xiaomi Admin answered him, that the new Hub does not support LAN.