I have only seen the them on Chinese websites, however I saw a post on German forum where guy actually purchased one and successfully installed on his CUX. It did not take him long to get this delivered. It was around 100 USD.
I hope this helps.
It’s a standard carrier box. I have one for my wife’s Etalian. Costed 50€ approx.
You can buy the rack and then fit any generic top box. I ordered from here, it's expensive but I couldn't find it anywhere else:
https://www.outdoordreams.eu/Top-Case---Carrier/carrier/Super-Soco-Luggage-Rack/
Also be aware I was unable to install this myself because I couldn't remove the nuts on the bike. They are locked tight and require a professional power tool to remove it.