Im using UE5 which is arguably GUI heavier than Unity. You can get around a lot of the GUI-heavy stuff by using C++ in preference to Blueprint, and/or developing some tools to help you decompile/recompile Blueprints.

It has a pretty cool remote control plugin you can install which can be used to simplify a lot of test cases through automation.

I have a relatively large amount of experience with UE4/UE5 and C++ though, so it's probably not for the absolute beginner or the faint of heart.