Maria Campbell provides a post on installing the latest version of Python on Mac OS Catalina and overriding the old default pre-installed version. And it even uses Homebrew and not some gnarly steps.
I finally did it. I successfully installed Python version 3.7.7 via Homebrew on my Maclaptop with OS Catalinainstalled.
For those of you that still might be trying to figure out how to do this, I will walk you through.
The reason why I was eager to make sure that I had the latest version installed was because I am working on publishing (open-source) teaching-related documentation on Read The Docs, and I need to have Python installed in order to be able to install the programs necessary to publish there.
The default 2.7.17 version of Python was retired this past January 2020. I had tried back then to replace it with Python 3+, but was unsuccessful at the time.
Install Python 3 Mac Catalina
Install Python Mac Catalina Download
Get code examples like'install python macos catalina'. Write more code and save time using our ready-made code examples. The macOS 10.15 SDK provides support for developing apps for Macs running macOS Catalina 10.15. The SDK comes bundled with Xcode 11 available from the Mac App Store. For information on the compatibility requirements for Xcode 11, see Xcode 11 Release Notes.
They key appears to be also adding the following at the bottom of the .zshrc file to update the path to the newly installed version of Python via Homebrew:
Install Python Mac Catalina Update
See all the steps in the blog post here and podcast here.