Gentoo.

wiki.gentoo.org/wiki/Handbook:AMD64/Full/Installation

It is unlike installing any other distro. The installer should be very comfortable working from the Linux command line. This is why he has been writing an install script for LCNC installs. I'd wait for the script unless you are willing to learn and spend the time going through all the features and settings in the handbook..

Just fair warning, Gentoo out of the box does not have all the necessary packages for LinuxCNC, you may encounter compiling errors as not every single combination of options has been tested, and typically with Gentoo, you are expected to build your own kernel yourself. Because of this, kernel problems, performance issues, and issues with X.org/desktop environments for those new to Gentoo are quite common.

Please note, the Gentoo image I am working on is quite custom and will not be fully compatible out of the box with a typical vanilla Gentoo install. I.e. Gentoo pushes releases out that are built on Clang/LLVM+musl, _or_ gcc+glibc. My image is neither, it is 99% built on Clang with very few exceptions to build with GCC, with glibc as the C library.

Gentoo musl is trailing behind with various packages such as rust which is why I went this route, and Clang is the default compiler for AMD, Google and OpenBSD now. If you start switching things over without properly rebuilding and rebootstrapping the toolchain, expect major breakage.

Due to the complexity of Gentoo, I can really only help with problems pertaining to the image/installer I'm working on once it's done. It's most of the way there. If you run into problems on your own time, I personally cannot support it, however the Gentoo forums and their IRC channel is quite helpful, their community is quite active!