What I want to do is not have to have a unified build system for multiple platforms and ABIs without any problem, but for some reason, to target anything apple, I have to use a physical apple machine.

It's absolutely abusing market position, because it ends up being that in my profession, you end up purchasing mac computers for the whole office, because then you can target all platforms without any fuss. Not because the hardware or software has any merits, but because they artificially restrict these use cases so that's the only option to target a significant market.

https://github.com/tpoechtrager/osxcross

> Please ensure you have read and understood the Xcode license terms before continuing.

According to the EULA you may only use the SDK on Apple-branded computers. But you can use Linux to cross compile to Apple.

Do the Visual Studio build tools have more permissive license terms? AFAIK you can have clang-cl on Linux, but you do need a lot of the SDK for it to be useful. No experience there.