macOS is described as 'Unix-based operating system for Macs, excels with an intuitive UI, robust built-in apps like Safari, and strong security via FileVault, Gatekeeper, and SIP' and is a leading operating system in the os & utilities category. There are more than 100 alternatives to macOS for a variety of platforms, including Linux, Self-Hosted, BSD, Mac and Windows apps. The best macOS alternative is Ubuntu, which is both free and Open Source. Other great apps like macOS are Linux Mint, elementary OS, Debian and Fedora.
It has a similar-looking toolbar, and also uses command-line interfaces quite a bit.