TL;DR Was the ancient Shandorian civilization technologically advanced? Likely although not confirmed.
To understand the ancient Shandorian civilization there's a lot of lore that needs to be understood about the One Piece timeline, the moon peoples, their successors and the void century.
Over the course of the cover story "Enel's Great Space Operations" spanning Ch 428-474 we learn of the ancient moon civilization, the Birkans including their history, impressive technology and the reason they eventually had to leave. To summarize, long ago there was a civilization of winged moon people called the Birkans whose technological feats included sentient robots and ships capable of interplanetary travel. Running out of resources on the moon they used these aforementioned ships to carry them down to the White sea with one particular group making it all the way down to the Blue sea.
The descendants of the moon people can be identified by the wings on their backs which include the White sea civilizations of Skypiea and Birka (Enel's homeland, not to be confused with the ancient moon civilization), and the Blue sea Shandorian civilization on the island of Jaya. When did the moon people come down to the Blue sea? We do not know exactly but according to the tombstone for the city of Shandora Robin translates in Ch 261
the city of Shandora prospered in the year 402 (~1100 years ago) meaning it was settled by the moon people some time before then and fell ~800 years ago which places its fall around the tail end of the Void Century. In Ch 272 Robin translates some text inside the city of Shandora written in the language of the Poneglyphs,
The text refers to how the city of Shandora fought to protect its Poneglyph against an enemy and as a result, their civilization was destroyed and their history erased. While some people survived and became the Shandians the Shandorian civilization was gone, their golden city fell to ruin and their history and literature was lost in the void.
Speaking of the void and the fall of Shandora, what happened in the Void Century? I have no idea and that's kind of the point, just about nobody knows what happened in the Void Century. What we do know is that it was a period of history that started ~900 years ago and lasted around 100 years. While historical records exist of the time before and after the Void Century, what happened during these hundred years can only be found on the Poneglyphs. Researching the Poneglyphs/Void Century is forbidden by the World Government and punishable by death. In Ch 395, Professor Clover of Ohara reveals a basic overview of what he thinks happened,
We do not know if the great civilization he was referring to was Shandora but we do know the World Government is entirely capable of suppressing all knowledge of a once great civilization and that Shandora fell during this time. Meaning Shandora was once a powerful civilization and may or may not have been technologically advanced but due to being erased from history we CANNOT know if this was the case.
In the main story of One Piece, in the year 1122 (~400 years ago and 400 years after the fall of Shandora) we are introduced to the Shandians through the first hand accounts of Mont Blanc Noland (Ch 287-293). The Shandians are descendants of the Shandorians but are a rather low tech society bearing none of the hallmarks of the ancient Birkan civilization (robots and flying ships). They live in a village quite far away from the ruins of Shandora. In 1127, they are launched along with half of Jaya by the Knock Up Stream into the White sea island of Skypiea.
One thing to note is that while the Shandian's don't seem to have much of the moon people technology, Enel's flying ship he uses to reach the moon is reminiscent of the moon peoples ship and given he's from Birka they may have had the blueprints/knowledge of interplanetary ships inherited from the moon people.
