The Fractal Architect 4 render engine, given robust, quality drivers, has worked on all versions of Mac OS (except partially on High Sierra because of driver problems). AMD, Nvidia, and Intel GPUs all can be used. It supports CUDA and OpenCL.
The Apple CPU OpenCL driver has always worked over the last 7 years, so when the GPU drivers are defective, users can still use the app with CPU rendering.
Nvidia GPUs and CUDA are also supported (but not in the FA 4 Mac App store version because of app sandboxing) on both Mac OS and Windows 10.
It has been ported to Windows 10 and there it also works with AMD and Nvidia GPUS. Intel GPUs worked with 1 version of Intel’s OpenCL drivers but not with a later OpenCL driver update. (So the Windows platform is also affected by driver quality issues.)
Intel’s OpenCL driver for CPU on Windows 10 does not work with the FA 4 render engine.
The render engine is a fantastic test case for GPU compute and can be used by OpenCL and CUDA driver developers to validate the quality of their drivers. The render engine itself is open source and licensed with LGPL license.
The app itself is even easier to use for driver quality testing on Mac OS. Metal is supported by the app (but not in the open source render engine).
Earlier versions of the render engine have worked on all versions of Mac OS since 2009.