The code for this project was developed using Adafruit's CircuitPython and documented in John Park's tiny museum project. Head on over there and follow the tutorial to setup CircuitPython on your HalloWing M0 Express.
Mu: Python IDE
Check out the Mu Python editor for writing CircuitPython code you can easily save and load to your Adafruit supported hardware. Use the built-in serial console for debugging and the plotter for visualizing data. Download the software and check out the learn guide for installation help.
Once you have CircuitPython installed and setup on the HalloWing M0 Express, you can download the assets for this project. This includes bitmap images of the Mac OS boot screens and chime audio wav files. These are included in the download link in the 3D printing page.
The tiny museum project also covers how to create custom images and audio assets. If you're interested in creating your own assets for this project, be sure to walk through this page.
The Mac OS chime sounds were recorded from this YouTube Video. It also has "crash" sounds.
The Mac OS boot screens were found in this blog post that features several others.