It turns out I have hit a bug with Godot's PackedScene not saving my dynamically generated doors for the level (details here), so I cannot continue until the bug is either fix or someone comes and tells me I was doing it wrong lol.

If you want to see what my game was about, take a look at this GIF:

Luck is the religion of the weak, so, I wish you all the success of the world to those left competing! :)