What's the correct way to use user local python environment under PEP668?

I have tried to install any python packages on Ubuntu 24.04, but found I cannot do that as in 22.04

PEP668 said it is for avoiding package conflict between system-wide package and user installed package.

example:

$ pip install setuptools --user
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/python3.11/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.

But if I do that with pipx:

$ pipx install setuptools 

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

I am really confused with current rules and can not install any package to user local env.

How can I manage my user local environment now? And how can I use latest pip (not linux-distro version) and other packages by default for current user?

My Environment (docker):

FROM ubuntu:24.04

# add python
RUN apt install -y python3-pip python3-venv python-is-python3 pipx

USER ubuntu
WORKDIR /app

I know I can use some env manage tools (pyenv) to do that, but is there any built-in method to bring my user local env back?

from What's the correct way to use user local python environment under PEP668?