[cryptonector]

This is clearly a simple proxy that can scale horizontally. That should get you the task completed. The SO_REUSEPORT/epoll/io_uring stuff is definitely a point of research (and for TCP too, not just UDP), but it's doable (here it helps if the senior eng. applicant can read Linux kernel code and is resourceful). If you're going to be exceeding a 10GB NIC's bandwidth you'll have to talk about using multiple IPs, DNS tricks, client smarts, etc. And all of this assumes that the HTTP backend can go at least as fast as the UDP proxy, which... is a big assumption, because it's much harder to get an application to perform as fast as a proxy, and TFA is already asking a lot of a proxy.