Is there a list of which python packages are imported by default? or available?
The official documentation only states:

Python 3.9.
Most libraries are already imported automatically for your convenience, such as array, bisect, collections. If you need more libraries, you can import it yourself.

Imported automatically:
sys, operator, functools

Available, but not automatic:
numpy

Available, but corrupted:
platform (just a string instead of a pkg)