What does wxPython need to run successfully?

The error you're encountering is likely to be a "brew-hole" (a.k.a homebrew installation/compatibility issue for wxpython v3 and sometimes v4).

To test some issues that might be at hand perform the following in your pyenv:

1. python --version
2. python3 --version

How are they installed? Did you use brew?

3. If brew or any non-anaconda: uninstall all.

4. Then : reinstall python via the anaconda 2019. (xx >04) packaged version and it gives you 3.7.4 or 3.7.5 depending on what you choose.

5. reinstall via conda/pip cmd-line the required packages that are not with default install.

Anaconda "base" is your default environment.

6. Then conda create --name myenv where myenv is any name you give your environment. For example "myPythonwx408" environment.
7. cmdline: conda activate myenv

... and tada.. up you go...

If the error persist in anaconda env you can post the environment.yml file so I can recreate your environment for testing.

You mention "virtualenv". Is that the actual virtualenv package or just what you are calling the pyenv instance? If the former then try python -m venv instead. The virtualenv package still hides the framework-ness of the parent Python, even after all these years. The venv package is included with Python3 and is a much better/simpler implementation of the concept.