With VoiceOver enabled, create an iOS app in Xcode. Add a second scene to the storyboard, then a button to the first scene. You want to control-drag from the button to the second scene to make the button show the scene, but you will do it with VoiceOver.
1. Interact with the editor area, then the main.storyboard group, then the canvas, then the scene with your button, then the view controlser, then the view.
2. Find the button and hold down vo-comma until the menu of modifiers appears; arrow to 'control' and press space or enter.
3. Now stop interacting a few times, focus on the second view (the one to be segued to) and press vo-period to drop the button.
4. For me, Finder immediately gets focus. Xcode doesn't crash, it just goes to the background. When I command-tab back to it, there is no menu from which I can select a segue type. Sometimes I stay in Xcode, but even when I do, I simply can't make a segue this way.