After reading all the documentation, all the examples that are in the repository and searching the whole internet for examples of implementation, I did not find the example I need.

Unfortunately, everywhere it is about initialization of broker and actors in one file, which is not very suitable for production code.

Here is an example of the implementation I was looking for:

FastAPI

app/core/dramatiq_service.py - broker initialization
app/tasks/foo/tasks.py - multiple actors
app/tasks/bar/tasks.py - multiple actors
app/main.py

first terminal: uvicorn main:app --host 0.0.0.0 --port 8001 --reload
second terminal: dramatiq core.dramatiq_service

All actors are initialized and run correctly.