The idea behind `piku` is that it provides the simplest possible way to deploy web apps or services. Simplicity comes at the expense of features, of course, and this document tries to capture the trade-offs.
Ways to improve upon that (short of full containerisation) typically entail the use of a `chroot` jail environment (which is available under most POSIX systems in one form or another) or Linux kernel namespaces - both of which are supported by [uWSGI][uwsgi] (which can also handle resource limiting to a degree).
As to runtime isolation, `piku` only provides `virtualenv` support until 1.0, and all Python apps will use the default interpreter (Go, Node and Java support will share these limitations in each major version).
Supporting multiple Python versions can be done by deploying `piku` again under a different Python or using `pyenv` when building app environments, which makes it a little harder to manage using the same [uWSGI][uwsgi] setup (but not impossible).