On Windows, renders readably.
On Mac OS, choices are rendered microscopically small, unreadable!
Using python 3.13.5, wxpython Versions/3.13/lib/python3.13/site-packages (4.2.3)
If I go back to using wx.App instead of wx.PyApp, the dialog renders normally, like on Windows.
The reason I was using wx.PyApp (only on Mac) was to get my python app to the foreground after starting it. It is annoying to have to use the keyboard or mouse to switch to the app that you just started, unlike most Mac apps.