How to use the eyedropper in the gradient tool Affinity Photo

[melior64 26]

I recently saw this post by @ivanozzo sharing a great resource for gradients and colour ramps, but I couldn't figure out how to easily use the eyedropper tool with the gradient in order to copy them into Affinity Photo.

After a long time playing around, eventually I sussed it out - so here's a tutorial for anyone else who needs this!