About the dummy player controller
The ULocalPlayer always spawns a local & dummy PC (class is APlayerController)
The server will later create the real PC instance and assign and replicate it to the client.
You can find this dummy spawn and details about it at ULocalPlayer::SpawnPlayActor.
// The PlayerController gets replicated from the client though the engine assumes that every Player always has a valid PlayerController so we spawn a dummy one that is going to be replaced later.
// Look at APlayerController::OnActorChannelOpen + UNetConnection::HandleClientPlayer for the code that replaces this fake player controller with the real replicated one from the server