How to use displacement maps from Photoshop into Affinity Photo tutorial
You can use displacement maps in Affinity Photo and the displace filter, you can use the displacement maps for use in Photoshop (but see below for a big but). You can use the 1000s of displacement maps for Photoshop etc
Weirdly, you cannot use the PSD files via the Affinity Photo displace command but you can use them in PNG format.
Quick solution is then to
open the PSD file
export to PNG format
load map from file (select the PNG file)
You can also use the same files then via the gradient tool and the fill layer as a bitmap and you can rotate and scale etc the items.