For fully static sites it is hard to compete with "upload files to S3 and host via CloudFront" with the caveat that it costs about 10 cents per gig*month to store data and 10 cents to send a gig out.
If your usage will be small enough that those prices aren't painful then you get true 24/7 availability, reasonable performance and a lot of convenience.
Add the python server and your costs might go up. For applications that are mostly static but have an occasional form (say email newsletter subscribe/verify/unsubscribe script) the economics of the lambda functions and the web service gateway are great. If you are going to have a python script called for every html page (e.g. conventional CMS) you might not like the economics.
You could run a small cloud server with the dynamic parts, you will always feel some tradeoff between "throw a lot of resources at it and be delighted with performance" and "try to save resources and find your server upside down with the casters up occasionally"
As for the rasp pi that was a fantasy that I remember internet anarchists being into back in the days of Hakim Bey and Falun Gong. It seemed "liberating" to people to have the 23/6 availability and inconsistent performance of running a low-price server at home. It might feel good to you but the users won't appreciate it.
Today it seems something a conservative politician would do: host the web server to get welfare benefits on a rasp pi behind a slow connection.
