Does Xcode 26 still work on Sequoia? They usually stop supporting N-1 around March.
But it is possible to run even the latest Xcode 26.6 by directly executing Xcode.app/Contents/MacOS/Xcode, and Xcode will run. This trick doesn't work with Xcode 27 anymore though. If you try that, you'll see a warning message that says something like "Xcode requires macOS 26 to run".
Ah, the old "This program requires Windows 98 with Microsoft Internet Explorer 4.0 to run.". Some things never change.