Graphisoft is promising to add more commands with upcoming versions. Currently it's unknown, will Python commands duplicate C functions and commands.
If you need to build proper Add-On - the only way is to write it on C.
From version 24, Archicad has a new JSON Interface. It provides a way for external applications to automate ARCHICAD functions. It is a one-way communication from the external software to ARCHICAD.
The communication happens via HTTP using JSON messages.
GRAPHISOFT publishes an official Python binding for the ARCHICAD JSON Interface at the Python Package Index (PyPI). This package helps to establish the connection and hides the JSON communication layer.
When you are running a python script, the script sends JSON messages to Archicad and Archicad returns JSON responses back to the script via HTTP.