I wish they used them all, especially XDG_CACHE_HOME which can become pretty big pretty fast.

disable this system security feature temporarily,

This should be - if I’m not mistaken - possible using the pip env var I posted about earlier, like this:

PIP_BREAK_SYSTEM_PACKAGES=1 sudo apt install howdy

Or exporting it for the current shell, before running the installation

export PIP_BREAK_SYSTEM_PACKAGES=1

But I personally highly discourage it, because - AFAIK - if it even works it will mess up the deps in your system.

I’m no python expert but reading around it seems your only real solution is using a virtual environment, through pipx or venv as you already had found out, or using the

--break-system-packages

* Allow pip to modify an EXTERNALLY-MANAGED Python installation

  (environment variable: `PIP_BREAK_SYSTEM_PACKAGES`)

pip flag which, as the name suggest, should be avoided.

EDIT: After rereading I got your problem better and I was trying to read the source for Howdy to see how to do it, so far no luck.