io_uring doesn't really have equivalent[1], it can't batch multiple UDP diagrams, best it can do is batch multiple sendmsgs and recvmsgs. GSO/GRO is the way to go. sendmmsg/recvmmsg are indeed very old, and some kernel devs wish they could sunset them :)
Do you mean zero-copy rx by ZCRX? If so, io_uring should support that, but you need a kernel recent enough.
It supports both zero-copy rx/tx on tcp and udp afaik, and there was a paper from the google engineers that implemented zero-copy send/recv (originally for tcp only) showing that the whole endeavor was worth it when the payload was >= 20kb in size (iirc).
It could be interesting to see if that's still the case with current state of linux, memory sticks, etc.
I've looked up the links from when i dug into that:
I was expecting to see io_uring mentioned somewhere in the linux section of the article.