In December 2019, the Microsoft Windows 10 stopped Phone Number. The company's big plans with the Lumia and Windows Phone, haven't had the success they needed to compete with Android or iOS.
So Windows 11 Phone never became a reality. However, there is a free unofficial way that makes it possible, although the experience has some flaws. Project Renegade is a mod that allows users to test Windows 11 on Qualcomm phones Snapdragon, among other devices.
Using Project Renegade, Reddit user anh0l managed to run Windows 11 on his phone. anh0l he says:
I wanted to install Windows 11 on my old phone. Also, I've had experience running a linux distro (postmarket os) on my different phone, so I figured it wouldn't be any harder than that. I was wrong.. it took me about 8 hours trying to find tools and files that could work on my device (Mi POCO X3 pro). But finally, after 3 tries I got it to work quite smoothly. The only problem is the touch screen which is kind of messed up and flipped in half..
What is nice is that the operating system was installed on a rather cheap device, the Xiaomi POCO X3 Pro, which costs around $250-300.
In case you are wondering, Renegade Project is an EDK2 based UEFI firmware that has been tested and verified to work on various Appliances, including the MI POCO X3 Pro. In Microsoft's case, the Nokia Lumia 950 and 950 XL models are also supported, as well as the Surface Duo and Duo 2. You can find the full list of supported devices on this page on the official Project website.
anh0l recommends staying away from light builds of Windows 11 as things have been removed and may cause compatibility issues.