Almost but not quite. Mac sandboxing is optional and doesn't eliminate the signing requirement because Apple see it as a way for app authors to reduce the impac

Almost but not quite. Mac sandboxing is optional and doesn't eliminate the signing requirement because Apple see it as a way for app authors to reduce the impact of vulns in their app, not as a way for users to run untrusted Mac apps. Therefore there's no GUI to see whether an app uses the sandbox or not, or what permissions it requests, and apps can statically request any permissions they want and they'll be granted silently. Apple do this because their vision of solving software trust revolves around vetting people in the app stores. It's still very much code signing and identity based. Of all app platforms, only the web attempts to let people run arbitrary malicious code without risk.