Why can't I use "glcore" as a video driver?

My GPU clearly supports OpenGL ES 3.2.

Is it because Android devices can’t automatically support “glcore” yet, or is it something else?

I just want to attempt to run slang shaders with “glcore” because my device has better GL support over Vulkan.

Correct, android has no glcore driver. The only way to run slang shaders on Android is via Vulkan.