Major Spoilers for all Expansions - Some general things I didn't understand

[Cilia]

Of course.
It happens in Ultima Thule during the Omicrons' tribe quest. You restore the café we find in the MSQ right before Alphinaud and Alisaie lose their bodies to form the stairway.
In order to reopen the café, you need customers, so you start resurrecting the Soldiers, the Grebuloff and the guys whose name slips me right now (They summon that Sphinx like Boss, Ra-La, at the end) you can see their worlds of during the dungeon "The Dead Ends" and find out what they loved to eat the most.
One by one they start using Dynamis, recreating parts of their homeworld and even create more of their kind.

I haven't done the Omicron quests on account of abandoning crafting after 2.X...

... but the most likely answer, or at least the best I can come up with, is that while it's possible for the Omicrons to recreate things, we and the Loporrits involved have committed to an unspoken non-interference clause since importing all of the Omicrons' advanced tech into Etheirys would cause chaos. Besides which one of the central themes in Endwalker is embracing the ephemeral nature of life, so while resurrecting people with the Omicrons' tech is theoretically possible we aren't going to do so.