Found this excellent video about making modular projects in Godot using Composition. I like this a lot, it's a nice tidy way of working.

https://www.youtube.com/watch?v=e3H_nw4w5U8

Mastering Composition for Beginners in Godot

YouTube

@psychicparrot42 thanks for the link! Now I can get rid of the ugly onready code. Was worried this was just what I had to deal with, hard-coded rubbish.

I wish more tutorials actually taught good practice. (Mind you, maybe the tutorials I watched are old)