Good observation @SilverMoon - yes: regarding size and proof and why they would feel the need to do that.
Yes, remember that the inner sun is the realm of the Gods on this planet. The scriptures are repleat with imagery - and for good reason - of multiple kingdoms. Just look at this Jain Map of Earth - Manuṣyaloka (मनुष्यलोक - “middle planetary systems, specifically this earth planet”)
There are clearly three layers and the outer surface has been identified as the "telestial" while the Gods dwell in the "celestial" and beings of a higher order dwell in the "terrestrial" (likely inner concave giants and others who have made it back in, including John the Beloved and other "translated" beings who have that as their "headquarters" so to speak). I suspect the cavern world, aka hell/underworld/etc. is perhaps an outer darkness (due to the way the gravity well there could work makes this also would be interesting possibility for spiritual captivity and it is kind of the abyssal region of sorts). This all just fits ALL too well for this to be coincidental.......