MagicMac requires some atari or emulator, and Pure-C (you can also build the normal magic.ram with this environment). AtariX can be build on macOS only. Once you got AtariX running, you can use that emulator to build a new kernel for it
In my environment, i run Virtualbox on linux, using an image of macOS Sierra to build AtariX, then run it and build the magic kernels inside that emulator. The latter can also be done automatically (i use travis CI in my magicmac fork, which downloads aranym and a harddisk image with Pure-C and a few other tools preinstalled).
But they are different source repositories, so creating for example an installer can currently not be done in one step.