I can see how a zero-copy API would be hard to implement on some languages, but you could still implement something on top of io_uring with posix buffer copy semantics , while using batching to decrease syscall overhead.
Zero-copy APIs will necessarily be tricky to implement and use, especially on memory safe languages.
I think most GC languages support native/pinned me(at least Java and C# do memory to support talking to kernel or native libraries.
The APIs are even quite nice.
Java's off-heap memory and memory segment API is quite dreadful and on the slower side. C# otoh gives you easy and cheap object pinning, malloc/free and stack-allocated buffers.
Zero-copy APIs will necessarily be tricky to implement and use, especially on memory safe languages.