Currently the PythonSDK is open-sourced on Github.
Right now it supports:

• Borderlands 2
• Borderlands: The Pre-Sequel!
• Tiny Tina’s Assault on Dragon Keep: A Wonderlands One-shot Adventure

It is mainly developed by Matt Hurd / Lost_IC, FromDarkHell, apple1417.

Most conversations about the PythonSDK happens over on our Developer Discord