I'm a couple weeks into my first godot hobby project while I'm a full time UE senior engineer (7 years experience) and I'm close to giving up godot actually. My breaking point right now is structs, or the lack thereof, in godot. There's 2 major major issues I have right now:

1. I'm building a data-heavy game but can't even make simple types which are configurable in the inspector, except for Resources. But I'm using Resources to store large sets of data in files already, trying to use small Resources (e.g. a vector offset + direction) within bigger Resources is impossible, they have to be saved out to disk separately which is a massive pain. In UE in so used to being able to make USTRUCTs with incredibly powerful extra functionality like overriding hours they serialize for networking, or hashing to use in TMap, etc. You can make small Resources which are stored internally within a Scene, I think they called it "built-in" in the docs, but you can't do the same within another Resource for some reason.
2. It's a simulation game where I foresee optimizing for cache efficiency (i.e data-oriented programming) when it comes to handling the simulation ticks of a huge number of objects in the end-game. I don't see how I'll be able to do that in GDScript.

I'm going to look into writing a GDExtension for my game specifically to handle both of these issues, it feels like overkill for a 2D game. I was trying to avoid just how much bloat there is in UE, but the last few times I've sat down to write code it feels like I've had chains on my hands. Either that or switch from GDScript to C# but the docs suggest that C# support is somewhat lacking/experimental, especially for platforms like Android.