[GMcL]

100Gb doesn't actually go very far these days. One OTA map update will blow around a quarter of that.
It's impossible to have all systems loaded with the latest data on delivery if the car has been sat for a month or two in a compound. I suspect that 'free' volume to be insurance if the car needs to update in the first week or so otherwise the PDI process will be a bottleneck with reflashing. After that you have a Vodafone contract or, you use your existing mobile/network provider and make that the network hotspot.

Do new Volvo's allow WiFi connectivity to phones for network ?

You will need a good data contract with your provider if the car uses your mobile data for OTA updates and 'talking' to Volvo servers for satnav etc...