I finally figured out how to make it work again with the HomeKit Controller/Device integration. For everyone still struggling with the HomeKit based setup, try it this way:
It seems like a firmware update hid the auto-discovery of the Dirigera Hub behind a setting in the app. To trigger auto-discovery in Home Assistant you need to go to the hubs partner service settings in the app and try to connect it from there with HomeKit. But then don’t scan the code in the back of the hub with your phone! Instead now go to Home Assistant integrations page and enter the code there once asked for it while adding the discovered HomeKit controller. Keep the QR scan dialog open on your phone until setup in Home Assistant is complete.