Warning: Python 3.6 was not found on your system…I am left with no clear path to making this project run with the system Python 3 across just two versions of Ubuntu LTS. It doesn't work on Focal (Python 3.8) as-is, and if I update the Pipfile.lock, it won't run on Bionic (Python 3.6). It doesn't have shebangs for python3.6, as it expects to run on Python 3.6 or up. This is how SemVer works!
You can specify specific versions of Python with:
$ pipenv --python path/to/python
Maybe the answer is to build my own tools in order to run this in a way that suits me. Which is: I really want a build phase to create a tarball, which can be extracted and run in-place later. All the complexity of vendoring should be finished by the time deployment (from tarball) occurs, for reliability and reproducibility.
I do not want to write this project a third time, probably in a language I hate, just because virtualenv is both wholly inadequate, and central to Python tooling.
(Something like the way the awscli-bundle is packaged is an interesting start, but it still has to grind through a lot of code to "install" itself. It's not unzip-and-go. Also, I've got no idea how they build that in the first place.)