For dependency management needs, 99% of what you need can be done easily with vanilla virtualenv, vanilla pip, vanilla setup.py, and a Makefile. A small shell wrapper that sources bin/activate and runs your Python app is all you need to allow anyone to run your code without additional steps.

The biggest problem with Python packages isn't a dependency manager, it's that Python developers don't reuse and extend existing projects. They just keep churning out new similar projects with different features. All of the most commonly used Python packages are basically one-offs that use a bunch of other one-offs. This creates a cycle of reinventing the wheel and friction in ramping up on existing technology, due to all the extra integration work and split development, and later lift-and-shift into completely different dependencies that implement the same thing. PyPI is awash with duplicate abandoned one-offs to the point that just trying to just find a useful module to do what you want can take a long time.