OpenGL is far more beginner friendly than Vulkan. Vulkan (along with DirectX 12) is an API designed for professional graphics programmers, whereas OpenGL is a lot more accessible and manages a lot of state for you under the hood.

And, to save you some time with debugging, use RenderDoc to debug your graphics pipeline: https://renderdoc.org/

https://learnopengl.com/ is my favorite beginner resource for OpenGL

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as an aside, I like DirectX better than OpenGL, but you said Linux, so...