FNU is not compatible with any OS except OpenProninx.

FNU - Foundry Not Unix

FNU is the official set of utilities (both for the kernel and the userland) for OpenProninx (hence the official name, FNU/OpenProninx). Our main goal is to ensure that our operating system doesn't port a ready-made userland, such as gnu-coreutls, but rather writes its own, tailored to the needs of the OS itself. We are strictly against copyleft licenses, and our source code is distributed along with OpenProninx under the BSD-3-Clause license.

FNU is not....

Not an operating system. OpenProninx is the operating system.
Not a GNU replacement project. We are not trying to reimplement bash, coreutils, or glibc. We are building what OpenProninx specifically needs.
Not a compatibility layer. FNU software is written for OpenProninx. It does not aim to run on Linux or any other system.