https://wccftech.com/macos-catalina-runs-on-dedicated-read-only-system-volume/

Apple has released a number of bug fixes with the public release of its latest macOS Catalina 10.15, closing some serious security holes, as we reported earlier. Along with the patches for vulnerabilities, the new major release of Apple's desktop operating system also brings several security and privacy improvements.

Among other enhancements, macOS 10.15 offers better protections against tampering, an improved Gatekeeper, and the ability to locate a missing device even if it’s not connected to WiFi or cellular networks. In the release notes of macOS Catalina 10.15, Apple notes the following security improvements and features: