Because native git submodules are buggy and unreliable
checks-out or updates repos depicted in the current folder's fgs.json file. The binary can be installed anywhere that is reachable from $PATH.
If branch is missing in the fgs.json, "main" is assumed by default.
Makefile.sample contains code that can help execute mac, linux or windows version of the binary, depending on the system.
Implementation of Faux Git Submodules is written in Go and native builds are provided for a variety of platforms. You can find them under build folder. These are, probably, easiest to use. However it is impossible for the authors of this utility to provide a native build for every possible operating system/cpu architecture combinations. If you don't see the platform you are using, you can build yourself, or you can use the python version, given that you have python3 on your target platform.