Probably makes sense mostly on Mac. Right now, it's common for developers using Macs to install GNU coreutils from Homebrew as a first step to ensure scripts and build systems that were originally written for Linux still work. Macs give greater ease of corporate device management, so Macbooks are a fairly typical compromise for companies that need to give developers a Unix environment but still want to maintain the level of control over endpoints you'd get with Windows.

I'm sure there's desire out there for a pure-Rust close-to-POSIX userspace you can put on top of Linux, but I don't exactly see a whole lot of progress toward that. At minimum, you'd need coreutils, findutils, diffutils, tar, grep, sed, compression libraries, crypto libraries comparable to OpenSSL or GnuTLS, an editor, a POSIX shell, an init system, a service manager, system-wide DNS and DHCP. Going beyond pure POSIX to a more practical server distro would probably include a PGP implementation, a package manager, sudo or equivalent, ssh, iproute2, probably many other things I'm forgetting.

uutils seems to give you findutils and coreutils. ripgrep is not a drop-in replacement for grep. I'm sure there are other "rewrite it in Rust" projects out there I don't know about, but low-level system utilities aren't exactly the gloryland most developers are interested in rewriting and POSIX includes a lot of stuff.

Frankly, I don't think this is a realistic terrain for any single organization. GNU itself took over a decade to get a practical distro and that was only because other developers provided a kernel, package managers, boot loaders, crypto, and what not. And the GNU project is not really a single organization. It encompasses many people from many different employers. Systems software in general wasn't as fragmented. If you were working in the space at all and cared about being cross-platform and collaborating across organizations in the 70s and 80s, you were using C. Everything else was proprietary. If we're ever going to get something comparable but in Rust, it's not going to be from a single Github org like this.