How does the App use the virtual device to obtain the experience QR code?

If you just want to use your mobile phone to experience the control, you can open the App and scan the QR code in the second step of creating the product.

If you create an MCU-connected product, in addition to the experience in the second step, in the third step, you can click "Device Debug" to receive instructions from the mobile client like a real device, or simulate a real device Report data and debug the App interface.