Tears of the Kingdom has 152 Shrines, so solving them all isn’t easy. This reward is surprising and bizarre compared to Breath of the Wild, which has 120 (you can see what you get if you find all of them here).
The final Shrine shows some unique text and suggests visiting the Temple of Time as a reward for skipping the two cutscenes at the end of every Shrine for approximately 165 hours.
Tears of the Kingdom begins on an island with a temple of time, and the statues of King Raura and Queen Sonia are not references to the ruins at all. I don’t know who would make that mistake and search the ruins for arguably too long for a reward, but it’s worth going up into the sky to find a chest.