never dealt with Emilio's, but...
There's a lot of different ways to disable/enable a player. Probably what I would direct you to take a look at are signals within Godot. Basically give your dialog the ability to emit a signal, make your player listen to that signal, and when it sees that Signal, lock up. Could be as simple as adding a boolean value and as long as that value is false, do your movement as usual.
Other nice thing about signals, is that multiple things can listen to your signal. Your camera could blur the background so your character closeups pop more. Your textbox could use that as a signal to appear.