It’s manageable with eBPF instead of seccomp so one has to adapt to that. Should be doable.
There is now a memory buffer that the user space and the kernel is reading, and with that buffer you can _always_ do any syscall that io_uring supports. And things like strace, eBPF, and seccomp cannot see the actual syscalls that are being called in that memory buffer.
And, having something like seccomp or eBPF inspect the stream might slow it down enough to eat the performance gain.
Think of io_uring as a pair of unidirectional pipes. You shove syscalls and (pointers to) data into one pipe and the results (asynchronously) gush out of the other pipe, errors and all. Each pipe is actually a separate block of memory shared between your process and the kernel: you scribble in one and read from the other, and the kernel does the opposite.