Cannot buy Windows 11 retail version

Why can't I buy Windows 11 retail version yet? It's not available on Microsoft Store website or any of the retailer's website. Microsoft and other retail stores is still selling the old Windows 10 retail box with USB but nothing for Windows 11. What if I need to sell the old PC including the original copy of Windows 10 and then use an iPad with Safari browser to buy Windows 11 and all the components to build a new Windows 11 PC.