Thanks for sharing! As someone who's not familiar with graphics programming, i would say recommending to start with DirectX is probably the wrong choice: it looks just as complicated as other solutions, but will lock you into the Windows ecosystem. In contrast, OpenGL/Vulkan are widely ported. Same story with the undecided recommendation for Unreal/Unity/Godot: only Godot in those three is free-software, and has an amazing community. Even if you end up using something else in production, it's probably the good place to start since you'll find friendly people and the source code to dig into in case you run into oddities.
As an aside, I was curious about "The technical interview [LEAKED]" but the linked article links itself to dropbox which won't let me download it without an account. If you really want to share that piece of content, maybe consider uploading a copy on your blog or Internet Archive? Thanks for the read!