The os.getenv function called from a Python program running using ADDRESS USS USSCMD is returning "None" instead of the contents of the z/OS system symbol.
The z/OS system symbols are not directly available to be retrieved by the Python program using the os.getenv function. This function can only be used to retrieve USS environmental variables.
This type of variable must be set in the STDENV file pointed by the OPSUSS JCL or in the script that calls the Python program:
export SYSNAME=$(sysvar SYSNAME)