Hey, you can look here for a different method to do varying density on the mesh :
That would work only on a flat surface, but you can then turn it into a sphere latter.
I think except if you really need to work non-destructively, you can work in different destructive steps.
It will be simpler rather than doing everything with Geometry Nodes, which is of course possible but more involved.
Like if the UV are destroyed it’s always possible to transfer them, or re-unwrap them latter, after having the geometry nodes applied.
Try to do a lot of tests until you find the proper workflow, then build the final.
that’s the key to these technically involved projects;