I contacted Silverfast asking if they would consider also making sure their plug-in SRDx works with Affinity Photo for Mac. Got the answer that SRDx requires OpenCL support, which Affinity Photo (according to them) does not provide to plug-ins. Reading some Photoshop forum threads it seems that Photoshop on MacOS supports Metal as well as OpenCL, which at least in part could be a factor to why some plugins does not work with Affinity.
I would like to propose a feature request:
Support OpenCL GPU acceleration on Mac and allow plug-ins to utilize this.
Dirk_Vau reacted to a post in a topic:
OpenCL support on Mac (used by some Mac Photoshop plug-ins e.g. Silverfast SRDx)