I'm a 3d artist for games and I often need to create ORM textures. ORM stands for (ambient)occlusion, roughness, metallic. The ambient occlusion map goes into the red channel, the roughness map into the green channel and the metallic map into the blue channel. I never managed to do this in Affinity Photo, working with RGBA channels in photo looks very complicated. In photoshop it's so easy, I just have to copy the texture map and paste it directly onto the channel.
Is there a way to achieve this? It would be great if Photo had such an easy workflow for managing channels, in PS it's as easy as copy/pasting anything into them.