A short video clip of the alleged PlayStation 5 boot screen and user interface (UI) has surfaced that appears to involve a devkit rather than a retail model of the PS5. The video shows a black DualSense controller being used to presumably start up the console, and then the boot screen and UI eventually appear on a monitor.
https://www.notebookcheck.net/Alleged-PlayStation-5-devkit-UI-leak-has-fans-in-a-tizzy-as-boot-time-is-longer-than-that-of-the-Xbox-Series-X.496545.0.html