My Jupyter Notebook offers an example that uses the API to output a CSV including lat/lon:
https://forum.inaturalist.org/t/tool-for-exporting-inaturalist-data-to-irecord-or-elsewhere/19160
Also, in the PyiNaturalist examples now there is a more detailed tutorial if you didn´t already see it:
https://github.com/niconoe/pyinaturalist/blob/main/examples/Tutorial_1_Observations.ipynb