Keep everything in settings.py and use environment variables (django-environ) to configure it.
In a project with tens and tens of apps and so many modules requiring configurations and easily reaching more than thousand settings key, keeping 1 settings.py has not failed me.
With the approach mentioned in the article, you'll get to a point where you'll be having so different setting module for each env.
01. local
02. testing
03. CI/CI
04. E2E
05. Docker
06. Kubernetes
07. staging
08. release
09. production
10. k8s_win.py
11. k8s_linux.py
12. k8s_mac.py
13. heroku.py
14. pie.py
15. home.py
16. vacation.py
17. ...
Soon you'll get to a place where you need to kind of merge 2 of them (settings/docker.py and settings/kubernetes.py) or worse, several of them and then hell is unleashed. You get confused, your team gets confused, the new team member is confused, no one has any idea where to look at.
Just keep it in 1 place, let your brain stay healthier and prevent early cancer.