one way would be to just write some Python code to instantiate the class and run it with PyRun_SimpleString. You can then use Python C-API functions to find the resulting PyObject in the root dict. Once you have it mapped to a Go variable you can i.e. read attributes or call methods.

Most of this is outlined in this example. Your instantiated Python class is just a PyObject.

https://github.com/christian-korneck/python-go/tree/master/py-bindings/outliers

Another way: To instantiate a Python class the pure C-API way, this might help:

https://stackoverflow.com/a/1147840/4039255