I think the dark side of OpenGL for beginning graphics programming is that debugging can be really frustrating! I really think learnopengl.com should have a mandatory section for how to use RenderDoc (https://renderdoc.org/) - it's night and day if you know how to use it.

DX11 suffers from the problem that there aren't that much high quality material comparable to learnopengl.com - I really don't like RasterTek which just dumps code at you without explaining things properly. Same for Metal - the best way would be to just download and read the example source code from the official Apple site, but it's rather unfriendly for beginners.