Hi Omaroo,
Welcome to Affinity Forums :)
Have you tried to assign an Exposure adjustment to a gradient overlay in the Overlay tab in Develop Persona?
I'm afraid it's not exactly the same since the overlay gradient is linear (not mirrored as in Lightroom - although you can apply more than one).
In Photo Persona, you can apply an Exposure adjustment (or any other one you want) and use the integrated mask (all adjustment layers have one) to define how the intensity of the adjustment will be applied through the image. Here you can add more stops to control the gradient (mask).
