smoke

I couldn't get your approach to work for me -- my layers are individual images which frequently bleed outside the canvas margins, and despite the mention of "trimmed" results above I find Export All Slices seems to export at a variety of pixel dimensions larger than the 0% opacity "canvas sized" pixel layer I group to each slice. In other words, the grouped transparent layer pushes the margins out to the edge of the canvas, but if the layer content already extends beyond the canvas, I can't get it to trim to the canvas. +1 vote for Export All Layers in Affinity Photo, creating a series of canvas-sized export files each preserving the relative positioning of the layer within (otherwise transparent) canvas-sized images. This would be useful for all sorts of mock-up and presentation work.