I'll tell what my big blank spot is that I've never found a good tutorial for is how to break down a design file into a working page. I do mostly backend and architecture kinda work, but frontend/mobile UI dev has gotten more and more important. I understand the tech and can write code that functions, but when I look at a Sketch or Figma design, I just have no idea what to do with it.
I think like anything else it comes with practise and some familiarity with the UI framework of the platform you're building for. You could try looking at something like dribbble and reimplementing some small widget or bit of UI in your platform. On mobile I've found things to become a little bit easier as the types of layouts are more restricted and designers tend to make use of the platform's stock UI elements more.
