Zardnaar
Legend
In this setting people leave on planets and moons within the Dyson Sphere. It's not a Hollow Earth setting, a Dyson Sphere is the size of a solar system in this case with hundreds of inhabited planets and moons inside.
Sounds like a Crystal sphere. Dyson spheres are usually a lit smaller than a solar system normally 1AU.
Even one that size is huge in area. You could fit the Star Wars Galactic Empire and WH40k Empire of man in it and use less than 1% of the surface.