Turns out, it more or less renders the modern web unusable — and that’s the point
The Economic Security Project is trying to make a point about big tech monopolies by releasing a browser plugin that will block any sites that reach out to IP addresses owned by Google, Facebook, Microsoft, or Amazon. The extension is called Big Tech Detective, and after using the internet with it for a day (or, more accurately, trying and failing to use), I’d say it drives home the point that it’s almost impossible to avoid these companies on the modern web, even if you try.
As Big Tech Detective is not on the Firefox store (yet), installing it requires "sideloading" it into Firefox.