Something that can help if you really need to unwrap an UV Sphere instead of using the subdivided plane warping is to change the poles topology.
Example a Sphere projection UV with a default UV sphere :
As expected from an UV Sphere, the poles are badly distorted
But now, if you change the poles topology to something like that :
Still a completely solid UV Sphere but the Sphere Projection UV will have made the poles really much better visually.
Only the very top of the pole will still be as expected distorted