Could be our world a dyson sphere? What makes me thinking of concave earth as Dyson sphere is:
-earthquakes could be caused by hitting meteorits in outer surface
-geomagnetic earth energy grid, as we see there are lines around the earth that could be energy points or those lines could be real metal beams. In the fact building whole sphere using metal shell wouldn’t be so efficient. But what if advanced civilization built only spheric structure like bridge. And the rest happened by itself like matter attracting from space dust
-dyson sphere and concave earth have holes on poles probably because of some kind of radiation from central sun
-if helicoentrics belive that we live outside then even in their world it would be stupid because meteorits could constantly hit the earth surface and in their thinking civilzation should go to the inner surface
-tell helicoentric now not about concave earth but about dyson sphere this is so sci-fi and they will be interested