You can use swift package manager to create an executable target, which you can then run on macOS from the command line. Most frameworks (aside from UI) are shared between iOS and macOS like AVFoundation. If you don’t have access to macOS, you can still use swift package manager to build and run code on Linux or Windows, though you unfortunately won’t have access to any Apple frameworks.

I don’t think Apple has every really had great backwards compatibility. Apple’s last PowerPC computers shipped in 2005, and in 2009 Snow Leopard released with no PowerPC support. That’s 4 years of upgrades, which is about the same as it is now for macOS.

It an expression that means “I agree with what you just said”