It's MIT Licensed, you could take the project compile it, and put a price tag on it as a tool, and it would be legal. You could make a game that makes you millions of dollars and not owe a penny to the developers. You would be considered many nasty things probably, but legally speaking the MIT License would not forbid you doing that. You could also always contribute back. The restrictions of Unity are not the restrictions of Godot. You can make the millions you want to, you can redo the whole engine / tooling however you see fit. Just keep the original copyright notice and remember you have no warranty any of it works basically.
