Note that the cheap keys discussed here are real keys, but purchased with stolen money. Or keys for OEM versions, which were bought somewhere in excess of the required number. The fact of activation does not always make the operating system legal. Activation and license are not the same thing...
This question has been asked on the Microsoft Community site. The consultants said that at one time Windows 10 retail went on sale, 6 months after the release. Probably, Windows 11 retail will also appear 6 months after the release of the final version.