I want to run the Python program on the web.

It is impossible to run Python on the web.If you want to implement a converter, you can do this.

For example, This repository is the same django project, but converts PDF into an image. I think it would be good to refer to how this sauce works.

Usually, you can use ffmpeg, follow the subprocess, and return the result file.

Or, since it's a library with c, you can make an extension module and call it.

It would be easier to use projects that have already been wrapped, such as https://github.com/kkroening/ffmpeg-python.

It's a web service. You can use flask or django.