Actually general relativity says the space surrounding the earth stretches, not the earth itelf, so “the earth expands” is off target — in effect, anything near its surface stretches at the same rate.

The metric tensor math of spacetime curvature essentially explains how rulers change length (and seconds change duration) in a way that allows the surface of a massive object to continuously accelerate outward without the object getting any bigger! Of course, this defies our usual intuition about rigid objects, so it’s a challenge to think and talk about it.

Your hollow rigid sphere has less mass and will appear to have less attractive force, but it’s radius in meters is not changing. It’s easily measured outward surface acceleration is less.

This other article might be slightly clearer on that point.
https://davidlevitt.medium.com/the-secret-truth-about-gravity-f33f69eba7ef