How to manage multiple projects in Python ?

I'm seeking for advices from experienced people in Python development, and I can't really find any discussions/blogs/whatsoever on the internet.

I'm building the machine learning part of a web application. Right now,I have 4 different projects (two recommender systems, a data analyser and a retrieval system). To communicate with the rest of the application, I made an API using the Flask framework which is on the same server as the other projects. When a request comes, the Flask application calls one of the projects using subprocess.Popen and waits for the sub-process to return the results.

I want to organise this process in a better fashion, to make deployment, tests, updates and pipelines easier to handle. How do python developers usually the architecture of their applications in Python when they have several projects (possibly written by different teams) working together ? Do you create one meta project and deploy your sub-projects as packages ? What if you need to deploy them on different servers ?