What is the cheat there? That MacOS X is a single operating system, where both, command line tools the blog author knows and GUI tools, life in the same world, with da process model and same devices on a single kernel, unlike WSL? How is that cheating? Is my Linux desktop cheating as well?
A better comparison would be Docker for Mac, which has had several approaches over the years. Originally, Docker Desktop for Mac used VirtualBox in the background to spin up a VM that was then used for containers. It then moved to using HyperKit, which is the more “native” soliton but has downsides, largely around I/O and CPU usage, many of the same problems facing WSL1 and some of the edge cases with WSL2.
And it doesn't fit the requirements they stated: The docker container can't see the host's processes nor can the host see the container's processes. So the suggested "cheat" isn't there either.
Would doubtlessly be fun.
Before that, MacOS had (AFAIK - never seen it myself) the MPW environment that had a Unix-like shell.
And A/UX.
Practically an entire BSD kernel is run as a single "server" in Mach. In Apple's open source release, a majority of the XNU kernel code lies in the "bsd" subdirectory -- Apple's heavily patched 4.3BSD / 4.4BSD / FreeBSD hybrid.
Originally the idea was that having most of a BSD kernel running inside Mach would make it easy for researchers to run tools on their research kernel.
One suspects NeXT had a simpler motive: They just wanted to avoid paying money to AT&T. I'm not sure they had any particular interest in Mach itself. (Although obviously Mach's strange multi-architecture binary format paid off for them big time, some years later!)