February 2024: so finally the RetroArch Tutorial Part II is out, but please be sure to have gone through this Part I first 😊
21 April 2023: Added a short section as regards the Steam version of RetroArch.
20 March 2023: RetroArch 1.5.0 a.k.a. ‚The MacOS Release‘ (just kidding) was released - it is a huge improvement for Macs - https://www.libretro.com/index.php/retroarch-1-15-0-release/ and everything in this article also applies to the new stable build. I have not tested the Steam version, though because updating the newest Nightly manually is very convenient on MacOS, as also described below.
About this posting: As the new Vulkan driver for MacOS is a game changer for Retroarch in MacOS, it became necessary to update this entry. Don't be too afraid of this lengthy article, it's a checklist of what RetroArch is capable of, and the result of this work is an unmatched gaming experience, even in old-school arcade games.