I've previously written about OpenWatcom as a gateway to the ancient world. However, at that time, I focused on installing it using Docker, as OpenWatcom 1.9 only works on Windows and Linux. I'm not a full-time Windows or Linux user, so when I discovered that OpenWatcom's 2.0 series can be compiled and run on macOS, and it can run on ARM macOS, I was thrilled.
It's not mentioned on their website, and only in less prominent places like GitHub Issues. However, after testing it out, I believe it's worth sharing with others who share my hobby: writing old Windows (and DOS) applications but still wants to use their newest, shiniest MacBook to do so.
First, the compiler and platform SDK. To build anything on macOS, you need their official compiler and IDE. Xcode. Recently, they tried to slim everything down, so it'll be 2 GB-ish download from developer.apple.com.
Second, homebrew. This is optional if you know what you're doing. However, to smoothly compile OpenWatcom, you'd need DOSBOX command line and I feel the easiest way to obtain DosBox is using homebrew. Instal it from brew.sh.