Instead of using Blynk’s direct GPIO pin control, use virtual pins and code. Then, again, you can use Bridge to share information between App devices/projects. (although in theory, Bridge can also work with direct GPIO - I have never tried)
Since the App talks to the Server and the server to the Device, and the inverse from the Device through Server to App, the Bridge command from one device basically just tells the server to “control” another device by effectively spoofing that device’s App.