Another code editor, very similar to Visual Studio Code. In fact, it’s the same build from Microsoft’s vscode repository without the Telemetry. For all intents and purposes, VSCodium looks almost identical to VS Code as you can see from the screenshot below:

VS Code (left) vs. VSCodium (right)
So what’s the difference between the two?
In short, VSCodium has much less Telemetry report sent to Microsoft. It is the “binary releases of VS Code without MS branding/telemetry/licensing.”
This repository contains build files to generate free release binaries of Microsoft’s VS Code. When we speak of “free software”, we’re talking about freedom, not price.
Microsoft’s releases of Visual Studio Code are licensed under this not-FLOSS license and contain telemetry/tracking. According to this comment from a Visual Studio Code maintainer:
When we [Microsoft] build Visual Studio Code, we do exactly this. We clone the vscode repository, we lay down a customized product.json that has Microsoft specific functionality (telemetry, gallery, logo, etc.), and then produce a build that we release under our license.
When you clone and build from the vscode repo, none of these endpoints are configured in the default product.json. Therefore, you generate a “clean” build, without the Microsoft customizations, which is by default licensed under the MIT license
Should I Use It?
It’s not a black and white thing but the good news is you can always use both and decide later.
The argument is VSCodium is more private, the opposite argument is without Telemetry, Microsoft wouldn’t be able to improve the product and make it available for free. Just make sure you understand the pros and cons of using each product.
How to Install
The easiest way for Mac installation is with Homebrew.
If you have Homebrew installed, just open Terminal and type the following:
brew install --cask vscodium
The benefit of installing using Homebrew is that unlike Visual Studio Code, opening vscodium from a command line works right from the get go.
For the other platforms, please read VSCodium: Download/Install
Further Reading
VSCodium
How to Open VSCodium from command line macOS
VSCodium: Why Does This Exist
VSCodium: Getting all the Telemetry Out