Can I give you a tidbit of feedback?
If the instance is ephemeral, I need to manage everything in HOME and that's fine. For Python, that basically means using Virtualenv. That works fine at the moment for python 2.7, but 3.x on Debian requires the package python3-venv, which is not installed by default - and sure enough, it's missing in Cloud Shell.
It's a bit annoying having to apt-get install python3-venv every time. Any chance it could be preinstalled? It's such an essential tool for modern python development...