My Review of Cubic and We Connect for a T6.1 for what its worth.
Its taken me a while to figure out exactly what's going on here, this is the best VW software I have ever used, but even then it's not as intuitive a UI as my iPhone.
WeConnect is a stand alone service that allows you to monitor driving data and make your indicators flash on and off if you've lost your car in a car park. As a free service it is fine I wouldn't pay for it as it does very little to add to the driving experience, for example you can't set up your heating or lock and unlock the van.
Cubic is a data provider that utilises the eSim built into the van, the same one that VW use for free on the WeConnect service. It just provides internet access to the Infotainment system. The implementation is a little clunky e.g. if you goto to 'Shop' it still insists you have no data, but you do, I subscribed online for a free trial. The connection works well in an area where my phone data can't get a signal.
The system can also connect to the internet via a Wi-Fi connection to your house or even through your mobile phone if you set it for use as a personal hotspot. So that's 3 different ways of getting internet to your console, Cubic, Wi-Fi or Personal Hotspot.
Once connected you can stream music from the internet either through internet radio stations or Apple Music or Tidal subscriptions.
The second part of the system is that it can act as an internet router itself, so all of your travellers can connect their devices to the internet via the media system. The great thing about the media system is that it provides many ways to crack a data nut. Unfortunately it takes the data nut right off you as soon as you switch off the ignition.
My use case in the UK will be to ignore the Cubic data connection and use Apple CarPlay exclusively, giving the media player a data connection of its own offers zero advantage.
My use case in the EU will be to engage the Cubic data connection and stream media that way, its currently free! Long term I will use an eSim package deal I bought in France that is installed on my iPhone and leave that on as a personal hotspot. I imagine the best use case is to buy a MiFi and let everything attach to that including the car, that way all your fellow travellers can use the internet independently.
In summary, the Cubic data connection could be useful if your phone doesn't offer similar services, the fact that it switches off with the ignition makes it of very little use to the driver.