OK here's some pointless ramblings about Plato's sources for the Atlantis myth.
To be clear from the outset, I think Atlantis is very obviously a myth that is very obviously supposed to suggest something like a critique of Athens' political economy in the period after the Battle of Marathon.
With that aside, I think it's also obvious that Plato didn't invent the idea from whole-cloth, but acted much like a SF author and remixed and hyperbolized characteristics of his surrounding world.
So with that out of the way, I want to say that one of the things that really cooks my noodle is the Egyptian frame narrative in Timaeus. Without much justification, this frame narrative is really intrusive and distracting. There's a lot of layers of re-narration and a lot of text that expresses the Egyptians lording over the Athenians, both of which are uncharacteristic for Plato's dialogues.
To cut to the chase, I think that this is obfuscation about Plato's real source, Herodotus.
With Herodotus, we have an orator who was in the right place at the right time (the Olympics), talking about such things as the history of Memphis.
It is at Memphis, in Herodotus' Histories, that we get to a lot of the characterizations of Atlantis that a lot of us know: that it was ancient; it was a city of monuments built in devotion to a god of craft (Ptah in H; Hephaestus in Plato), it was destroyed by flooding (or nearly... the dams of Memphis are part of H's account).
The thing I really want to highlight here is Ptah, a creator-god and craftsman-god worshipped at Memphis. I think this strongly parallels the emphasis on industry and metallurgy that Plato describes in Atlantis.
Now a funny little thing about Ptah is that the workers at Memphis apparently wore lil' eggs as protective totems, & Herodotus names these "pataikos" after the statue of Ptah at Memphis.
You know who else used these??? THE PHONECIANS.
Per my understanding, the Phoenicians kept pataikos lashed to the front of their triremes.
So, and I'm just spitballing here, what if Plato heard about "Patai" from Herodotus (or people informed by H), he heard about "Pataikos" as associated with the Phoenicians and their legendary expeditions beyond the Pillars of Hercules, and what if Plato just decided to make an association between the two?
To be plain, I'm suggesting that Plato made Atlantis by remixing Memphis and Phoenicians.
(And now we wait for me to get nerdsniped by the millions of people more knowledgeable than me about Egypt, Athens, Plato, archaeology...)