Cool.

You can set up miniconda/conda even on an HPC, since it doesn't require sudo permissions. Here are notes related to conda and AFNI specifically:
https://afni.nimh.nih.gov/pub/dist/doc/htmldoc/background_install/miniconda.html

Basically, you create a directory of useful programs with dependencies in a very self-contained directory, say in your subfolder of your home directory. I think by just using the conda install recipes you will be set. It can be used to manage more than just Python, but these should be all you would need at the moment for Python 3.*, as noted in the notes above:
"matplotlib>=2.2.3" numpy scipy
... as pylab will come with matplotlib (and you would likely find matplotlib useful for other things, such as the afni_proc.py QC HTML).

--pt