How to create a Qt 5 ARM/Intel universal binary for Mac

I recently released a big update for my Mac ROM SIMM Programmer software which is written using Qt for cross-platform compatibility. As part of the update I wanted to release the Mac build as a universal x86_64/arm64 binary so that M1/M2 Mac users would be able to run it natively. It doesn't currently compile for Qt 6, although I think I can fix that in the future without too much effort. However, Qt 5.15.9 and later do support creating universal binaries out of the box, so I decided to figure out how to set it all up.

Even though I think I have pretty decent Google-fu, it was difficult to piece everything together to accomplish this goal. I'm hoping this post can serve as a reference for people in the future. These instructions are based on Qt 5.15.10 because that is the latest version that is currently open source. I did this on an M2 Mac Mini running macOS 13.5.1 Ventura.

Useful information for those that need it. I'm not one of those, but I'm sure some of you are.