https://gamefromscratch.com/battlefield-6-using-godot-game-e...
Planetenverteidigungskanonenkommandant looks neat though.
https://steamdb.info/tech/Engine/Godot/?sort=followers_desc
Battlefield 6 also uses Godot for its modding tools
There's also a free, MIT licensed Switch exporter, but it's in the Nintendo developer forums because of the NDAs.
If you understand how engines and rendering works in general you have an idea on how to implement something - but then you either run into A: a tool that can't quite do what you want but almost, B: an incredibly overengineered API that's somehow way more byzantine than OpenGL C: Some obscure quirk or bug of an existing feature that either works in a strange way, isn't documented, or is buggy.
In all these cases, doing the feature yourself is much easier than relying on the engine.
Particle systems are a good example for this.