in Affinity there are nice tools to stack photos (focus, panorama, ...) :-)
It is not possible to sent files from outside the program directly to this tools. But this would be nice, becaus of integration in Lightroolm and similar software. In the moment you can sent more photos to Affinity, but you are not able to use them in the stacking tools.
Of cause, a "real" Lightroom integration would be the best for the workflow. For the moment it will help, if there will be a way to send photos to all tools in Affinity (and reimport the result).