I've found that you can change the aspect ratio of a radial gradient in Illustrator to create an elliptical gradient, how do you achieve the same effect in Photoshop please?
Create the radial gradient on its own layer, whether directly or through the use of a gradient effect, then convert the layer to a Smart Object using
Filter > Convert for Smart Filters or
Convert to Smart Object from the Layers Panel flyout.
You now have a gradient that you can resize and transform using the
Edit > Free Transform as needed. Because it is a Smart Object, the transform is non-destructive, so you can adjust it later if the composition requires it.
If your transformed elliptical gradient needs to fill the whole canvas, make it larger than needed in a separate document, then drag it into your working canvas to give you the most flexibility.