FEMU VS xnvme

I guess I'm really not clear about how QEMU works. There's a QEMU SSD project here called FEMU which emulates a block device. If I wanted to basically have FEMU utilize a C++ compression algorithm instead of a C compression algorithm would there be anything I would have to change about QEMU itself, or can I just change it to use G++.

Basically io_uring grew a lot, the latest API offers incredible tools but there are very few examples in any language (xnvme and fio), and in particular I'm struggling to understand how to do it in Rust: where should unsafe code stop? should I simply expose the io_uring api as unsafe, or should I do more work in C and present the ring when ready to rust?

The foundation of xNVMe is libxnvme, a user space library for working with NVMe devices. It provides a C API for memory management, that is, for allocating physical / DMA transferable memory when needed. An NVMe command interface allowing you to submit and complete NVMe commands in a synchronous as well as an asynchronous manner. Similar to libnvme, however, with a focus on I/O performance and portability. Thus, xNVMe and the libxnvme library works not just on Linux, but also on FreeBSD, Windows, and MacOS.