inp2rad installation in externally managed environment

[CaribouFrequency]

I have encountered some difficulties in following the installation instructions for inp2rad on Ubuntu 24.04 LTS.

When I attempt to install pyinstaller by pip3 install pyinstaller, I am met with the following error message:

error: externally-managed-environment

× This environment is externally managed
╰─> To install Python packages system-wide, try apt install
    python3-xyz, where xyz is the package you are trying to
    install.

    If you wish to install a non-Debian-packaged Python package,
    create a virtual environment using python3 -m venv path/to/venv.
    Then use path/to/venv/bin/python and path/to/venv/bin/pip. Make
    sure you have python3-full installed.

    If you wish to install a non-Debian packaged Python application,
    it may be easiest to use pipx install xyz, which will manage a
    virtual environment for you. Make sure you have pipx installed.

    See /usr/share/doc/python3.12/README.venv for more information.

note: If you believe this is a mistake, please contact your Python installation or OS distribution provider. You can override this, at the risk of breaking your Python installation or OS, by passing --break-system-packages.
hint: See PEP 668 for the detailed specification.

I read PEP 668 and the Externally Managed Environments user guide page, as well as this discussion on the issue of installing Python packages system wide via pip, and it seems that some sort of virtual environment solution is the "correct" way to handle this problem.

So far, I have attempted to install pyinstaller via pipx, but although it installs successfully and can be invoked from the command line, it is not visible to the install.sh script. Additionally, I tried changing the pip3 commands in the script to pipx, but received the following message:

No apps associated with package inp2rad or its dependencies. If you are attempting to install a library, pipx should
not be used. Consider using pip or a similar tool instead.

There is a lot of friction in following these installation instructions, as they seem to be leaving out key steps at best, or contravening package management guidelines in a potentially system breaking way at worst, and they could be improved by adding some clarification about this issue.