Will probably be a while before could build a clean-slate unikernel with something like python, but doing what you want in a rumpkernel looks to be just around the corner:
https://github.com/rumpkernel/rumprun-packages/tree/master/p...
https://github.com/rumpkernel/rumprun-packages/tree/master/p...
We get into tricky situations when you need C extensions, e.g MySQL or PostgreSQL. Since extensions must be statically linked, you have to decide upfront what you want. Either extension can be compiled in, but including both in the package by default.... So a production Python build is fairly custom right now.
Nothing insurmountable, just haven't gotten the workflow perfect.
[0] http://projects.curiousllc.com/flask-in-a-rump-kernel.html#f...