In October last year, Apple releases a new version of macOS dubbed as ‘Catalina.' This latest installment of macOS includes new features, including new apps for podcasts, music, and TV (replacing iTunes), the ability to use iPad as an external monitor, a revamped Photos app, and many more. This can be obtained from the Mac App Store using a machine that supports Mojave, or by using the built-in downloading feature of the tool.

A copy of the macOS Mojave Installer App. In this guide, we'll walk you through how to use the tool to install macOS 10.12 Sierra on older Mac hardware, which claims not to. In many cases this turned out to be true, and with a few tweaks and amendments many of the 'unsupported' machines have been brought back into the fold by a tool by dosdude1, called macOS Sierra Patcher.

Definitely not 'dubious' third party software imho. He is a meticulous programmer who offers excellent support for the tool, and also a respected contributor on the Low End Mac facebook page.

Regarding the download of the full macOS High Sierra installer app – I have personally used dosdude1's patcher version for Sierra many times.

Is my mac ready for macos sierra