I'm currently using the trial version of Affinity Photo to see if this has been added yet. If it is, it's not available in the trial version, and I can't seem to find anywhere whether it has been added yet. Looking at the posts history, this was brought up 5 years ago and it still hasn't made it into the program.
This is a very useful tool for Photographers. I guess for now, I'll stick to Lightroom and Photoshop. Too bad because everything else seems to be just perfect for my needs. Hope it gets added soon