The library powerwallstats provides a simple class to access a Powerwall 2 directly from your local Powerwall gateway, not Tesla's cloud.
pip install powerwallstats
examples/show_powerwallstats.py provides a simple example use case. You will need need to setup customer email and password information on your Powerwall: follow the Tesla documentation to do this.
This has been tested on 4th March 2021 against a Powerwall 2 running firmware version 20.49.0 that requires customer login credentials to be presented. Tested using python3.
Alas Tesla do not appear to have released API documentation to customers, which seems short sighted. Details of the Tesla gateway API have been reverse engineered and further details are available from https://github.com/vloschiavo/powerwall2