Well, I get this far...
"Building the ROM
- Run build.ps1 (like in Step 4).
- The default compiled ROM is copied to bin/m12.gba."
Like in step 4? The only step 4 I see is... "Copy EarthBound ROM to bin/eb.smc."
Step 5 seems more likely, but when I duplicate that, I get "TODO: what's the Mac version of armips?" (I am on a Win 10 PC, and yes I've made sure I have the windows armips.exe in the "bin" folder)
And this is where I am currently stuck. Joined the Discord, but didn't find anything helpful there. If anyone has any input I'd appreciate it.