Creating custom windows, tools, details panels etc.

Hi, I’m an experienced coder (20+ years pro), and used Unity for my last PS4 project. In Unity I created quite a few custom windows to help with debugging and the development of the game. I’m trying to do the same with the Unreal project I’ve just joined and I’m hitting quite a wall when it comes to how to do this. I’ve watched the live training vid that one of the Unreal devs did, and I’ve read the documentation about plugins, but it all feels very opaque still.

The general line seems to be that if you want to learn how to modify the engine you should traul through the source code and see how that works, then just hammer away at stuff until you know what you’re doing. Am I missing something here or is this just one of the drawbacks of using Unreal ? Creating a custom window in Unity is half a dozen lines of code and it’s there. Doing the same in Unreal seems like a monolithic PITA.

Am I missing something ? Are there any good plugin learning resources out there that I’ve just not encountered yet ?