Thanks for the video. The main issue I'm experiencing which isn't covered in the video is with how you do the same thing with an alpha channel. Hopefully I'm not missing something but the expectation is to treat Alpha as transparency, right? If so that is exactly what I'm trying to avoid. I was trying to test this just now but ran into an issue I have to take care of some other work.
Also I want to be clear that I think Affinity Photo is amazing. I've only recently become aware of it and was extremely surprised with how much faster it is compared to photoshop. This feedback is not meant as a criticism of the app as a whole but a pain point with this type of workflow. I just hope I'm communicating properly so the AP devs will understand the issue game devs are experiencing.