Are these restrictions set out by the ISP or the dorm?
If you don’t do business with the ISP, then you don’t have to agree to and follow their terms.
So as long as the dorms doesn’t have rules against setting up your own WiFi, then you should be well within your rights to purchase an Internet connection from another provider, but since you are likely not allowed to get your own line installed, you are probably restricted to ISPs that provide a service over the cellular network.
Of course using a cellular connection will give you worse latencies for online games, but at least you can have your own WiFi with low latency for your VR.
If you want to be nice, you could then run as much of your Internet network over ethernet as possible, so you congest the air waves as little as possible, possibly only running the VR headset over WiFi, and maybe even only enabling the WiFi radio when you want to play VR. If all your WiFi devices support 5GHz, you might also completely disable your 2.4GHz WiFi, to leave the most congested frequencies alone.
To lower the chance of someone complaining about your WiFi, you should configure it as a “hidden network”, such that it doesn’t broadcast an SSID, and therefore doesn’t show up when people are looking for WiFi networks to connect to.
IPv6 does not require you to open your machine to the Internet, even without making use of a NAT. Sure you get an IP that’s valid on the whole internet, but that doesn’t mean that anyone can send you traffic.