and found that it is not, when I searched for it, I
had understood that a freeware, open source kind of MacOS kind of
clone,
is available, and, when I searched on the three word combination -
open
source macos - I found, in the results, the above URL.
So, as an observer, I wonder whether licencing restrictions apply, to
running MacOS on Linux, as a virtual machine.
If you click through the links on that page, it looks like Apple is
just linking to the source code for open source components used in
their operating systems (things like awk, bash, bind, bzip, etc.), but
the operating systems themselves are certainly not open source, and
cannot be legally used except in accordance with Apple's license terms
and / or applicable law.