Yes, it is nearly a 1:1 copy of io_uring, but unlike io_uring which applies to a single function, all I/O in the NT kernel is asynchronous. IOCP acts on file, network, mail slot, pipes, etc.

IoRing/io_uring is for files only. RegisteredIO is network only.

While Windows userland itself may be a 'mess' and archaic in it's own way (among the other anti-consumer bits), the NT kernel is technically quite advanced, not only for it's time, but at the present time.

David Cutler's team got the kernel architecture correct the first time. Linux still has a ways to catch up in certain aspects.