I guess with Dev Kit we get a controller and that controller is the android device where the apps will be installed and we don’t need to connect our phone. We can develop and run the apps on the controller without the phone.
Yes that is how it works. The compute unit is where you deploy your app (just connect it to your computer and use build and run in Unity to directly deploy on it). The controller can then be used for input just as you would with a phone. You can use scrcpy to see the android screen of the compute unit.
The controller is a small round device that is magnetically attached to the compute unit and can easliy be taken off to control your apps