While the keyword suggests a project called "Raven OS," it is important to distinguish this from an independent operating system. Unlike Linux distributions (such as Ubuntu or Fedora), Raven OS is not a standalone kernel. It is a heavily modified version of the Windows NT kernel—essentially Windows 11 Pro or Home, stripped down to its skeleton.
The forum post was eventually deleted. But if you search the deep web for tnzyl- Raven OS -Win 11 Extreme Lite-.iso -1.26... , you might still find a single seed. tnzyl- Raven OS -Win 11 Extreme Lite-.iso -1.26...