I would like to set some VisualStudioCode or PyCharm breakpoints for the script

https://github.com/PyPSA/pypsa-eur/blob/master/scripts/prepare_sector_network.py

and then run and debug it to better understand how it works.

Usually the scripts of PyPSA-EUR are run as part of a snakemake workflow.
Therefore, I currently see two strategies:

a) Create a run configuration (launch.json) that uses snakemake executable as program or

b) Run the script with python and mock the usage of snakemake in a main function of the script

=> What is the recommended way to do it and where can I find instructions?

Actually, the script file includes a main section at the end of the file:

if __name__ == "__main__":
  #...
  #snakemake = mock_snakemake(...)

However, that functionality seems to be outdated and/or serves a different purpose?
I created a corrensponding bug ticket here:

https://github.com/PyPSA/pypsa-eur/issues/1118

If instead a) is the recommended way to do it, could someone please provide an example launch.json and PyCharm run configuration settings file?

Related:

How to debug snakemake snakefile in visual studio code?