Its finish: ark-server-manager/z_unpack.py at master · TheCherry/ark-server-manager · GitHub
you can now decompress .z files with that:
python z_unpack.py "modfile.uasset.z" "modfile.uasset"
Hope it work correctly for bigger z files too, need some tests with decompressed files by the original ARK game.
At last there is a .mod file too. Its not hard to build it, but need to code that too.
Then you can start to develop your script.