What I want to do is have a screen come up telling the player that should they finish the level, but, not find all the elements needed to come up with a message telling them that, and have a couple of buttons to Retry stage, maybe Save or Quit if they so choose.
So, I have designed a UI/HUD element, with the intention of making it visible if needed, but, is there a better way of implementing this? Not fully implemented yet. IIRC, the Unreal engine had widgets for such a thing, but, I haven’t seen anything applicable in Godot other than UI/HUD to do this.
You could have a game over screen invisible until you need it, or you can instanciate it once the player dies. You can also switch to a new scene for this, if you want to.
I usually just have them part of the hud and invisible, same as a pause menu. This way I can order the tree correctly beforehand (e.g. which ui element will be in front) and I can have the last game state visible in the background.