I think my point was largely that Windows already has (1) from your list and it's already the gold standard on Windows, and has been available for some 25 years

I think my point was largely that Windows already has (1) from your list and it's already the gold standard on Windows, and has been available for some 25 years. I would be surprised if it wasn't part of the mechanism used in DirectStorage. io_uring does have a more ergonomic and POSIX API, but that's because it's on Linux! Fundamentally they're both completion port based replacements to polling for IO events and they're both capable of high throughput and horizontal scaling.