In this case the argument is focused on Apple forcing you into their ecosystem. Even though some packages might be generic, Xcode tools & codesign wont run and build on another OS then MacOS.
[1]: Yes, I know about WSL. No, that doesn’t count.
And this is not because no one wants to write a backend to target iOS, it's because Apple won't allow it. If you want to run native code on iOS, it must be built and signed with XCode on a Mac.
I will still note that debugging and monitoring are usually not going to work cross-platform - try to log to journalfs from a Windows system (wihtout using MinGW or similar).