I can't imagine OpenCL in any way being involved with the rendering of the UI. Maybe you're confusing it with OpenGL?
If you're having problems making use of an eGPU (that's supported by apple, which rules out nvidia!), you should report that. eGPUs will probably be a common use case.
If you're having problems making use of an eGPU (that's supported by apple, which rules out nvidia!), you should report that. eGPUs will probably be a common use case.