FastCGI provides that but the Python libraries are not that well documented, and sometimes unmaintained. For some reason this appears to be a "cultural" thing and not a technical issue.
I wrote a whole bunch of comments about my plans to work on that here (andyc):
I'm probably going to share my .wwz Python WSGI/FastCGI script. And show the hacks I did to deploy it on Dreamhost.
Long term I want to build FastCGI support into https://www.oilshell.org/ so the same problem doesn't exist there! i.e. the fact that you CAN deploy Python on many shared hosts, but nobody does because the ecosystem doesn't support it. Whereas the PHP ecosystem does support it, but the language is hard to learn.
I keep wishing we had webhosts that supported WSGI as 'shared hosting' with all the other benefits of a shared webhost.