That's a great list! decouple (https://pypi.org/project/python-decouple/) is a useful alternative for managing secrets. It converts values to the correct data type which is nice.
Another detail that matters deciding VPS vs PaaS - batch job processing. Heroku dynos restart once every 24 hours, longer jobs can't be scheduled.
Another detail that matters deciding VPS vs PaaS - batch job processing. Heroku dynos restart once every 24 hours, longer jobs can't be scheduled.