Press the Xbox button on your controller to open the guide menu. Select My games & apps, followed by See all. Highlight the Apps tab, and select the option for Wireless Display. Ensure the Wireless Display app is open and running on your Xbox One or Series X|S. You can now move to your external Android or Windows device and Connect or Cast to
Click on "Project" (If you don't see this option, you may first have to expand to view all the options, depending on your screen size) Click on "Connect to a wireless display". Select your desired wireless display. Profit. It's step #3 where things fall down. There is no "Connect to a wireless display" option on my desktop..