The author of WireGuard lamented that certain network pathway must be preserved for existing Apple infrastructure before WireGuard app can be approved and made available by Apple App Store.
So, there is no easy way to catalogue what kind of cellular data traffic unless we magically ran a network capture (WireSHARK) at cell tower level or root our iOS phone.
I do do know for iOS phones that cellular data traffic is drastically different than LAN-based WiFi traffic.