it is very much the title. if I have a code that use a non built-in library in my repository in github and someone copy it, this person will have to have that library installed, right?
Short answer, Yes.
Long Answer, Yes, but actually you do the following in order to make the script executable on other systems.
Add a requirements.txt file, which specifies the libraries used and needed to be installed. Usually, this is used in a virtual environment. This makes sure that the packages/libraries used will not get mixed up with the main python installation
This is a rough solution, and I would use it in very extreme scenarios. (I used it when I had to run a python code on AWS Lambda where the library I used was compiled in C beforehand.) You can directly copy the Library folder in your code and use it. Mind you, this will increase the code size and is Absolutely not recommended to be done.