I switched to the mac (back before the intel transition) because I became more productive writing apps after ~1 week of hobby fiddling, than I was at my day job doing win32 programming that I had done for several years.

This project doesn't tackle the reason macOS was so great: Cocoa.

I understand that the Supreme Court said in Google v Oracle that the use of APIs is fair use. Does that mean HelloSystem could re-implement all the Cocoa APIs and have Mac apps compile & run seamlessly?