I did not know that, I assumed they wrote pipx to mean pip/pip3. Thanks for pointing that out.

That might work but it is recommended to not install packages outside of virtual environments as it might lead to conflicts between versions across different projects.

You can run it in an virtual environment:

python -m venv someproject

source someproject/bin/activate

Then you can run the commands in the git README you posted.

pip …

Will will install the include files needed within this virtual environment. Alternatively you can do

apt install …

Instead of using pip. Your python script should run within the virtual environment.

Of all the things wrong with this, what sticks out to me how he seemed to be offended when you put down your boundaries. I feel sorry for your sister and i would share this with her. If he behaves like this with his own family, it doesn’t bode well outside of it. Yeah, perhaps replying wasn’t the best idea but i cannot put myself in your position vis-a-vis your state of mind at the time but it doesn’t take away the lack of appropriateness of his comments.