Yes, not many people measured NAT boxes at scale. "UDP NAT and Firewall Puncturing in the Wild" [1] this scientific article from our lab might be helpful. We also have UDP puncturing also working in a 3G or wifi setting with Android-to-Android mode, see "Kotlin-IPv8" link in here: https://github.com/Tribler/trustchain-superapp

[1] https://hal.inria.fr/hal-01597969/document