I’ve seen more than one post that some are having problems enabling Open CL in Darktable
I am running Pop_OS (Ubuntu Based) AMD CPU and a Radeon Nvidia 3060 GPU. More than enough necessary memory.
I could not enable Open CL
A bit of research pointed to Flatpak being the problem, a permissions issue.
From my repository, I downloaded Flatseal which allows one to enable/disable various permissions for any Flatpak apps installed on your system.
In Flatseal I found Darktable, and enabled Graphic accelleration, rebooted the computer, opened Darktable and OpenCL was available and running.
For any further questions - I am not an expert on Linux or Darktable, just did a bit of research and thought I’d pass it on!