I say "easy" in a relative sense, since we're talking about leveraging the use of automation here (and we know how that ends:
https://xkcd.com/1319/). And I'm assuming you have a decent engineer assisting in moving the scripts. they can learn the differences in the game loop and port over a lot of the high level scripts with a bit of thought. But not in a way that is easily automated.
And to be honest, I don't know how easy asset migration is (hence the question mark). it's a surprising pain point when moving from Unity to Unreal even if you keep everything as the industry standard FBX. I don't know if it "just works" in Godot or can be its own undertaking. Histoically it does mess up a lot of texturing and animations, even if you manage to get the base model in intact.