CloudFront -> ELB -> Pod running Gunicorn
Nginx will help you in performing the below items if you need some of them, Then I would say it make sense to add it to the stack 


Optimize the caching (you can also cache dynamic content.
Restrict access to the services (based on ips).
Implement basic auth for some services.
Load balancing traffic between different posds or services.
Rewrite URLS.
Pass extra headers or configs to the backend services.