The Euclid telescope, just launched today, will be able to observe galaxies out to 10 billion light-years. Here's the largest map I could find (1 billion light years) that includes the Milky Way, Laniakea, the Shapley supercluster, the Perseus–Pisces supercluster, and the South Pole Wall.
https://irfu.cea.fr/Projets/COAST/southpolewall-graphics.html
Even better, there are a handful of galaxies scattered here and there inside those voids.
If the Milky Way had been one of those galaxies then we wouldn't have known that other galaxies existed in the universe until the 1960s.
I just watched the entire history of the universe's newest youtube video and they touched on that... their videos always blow my mind
That's an oddly terrifying thought. Which makes me wonder... you know how stars sometimes get ejected from their parent galaxies and end up free-floating through the universe, all on their own?
Imagine if a star got ejected from one of those galaxies, managed to travel far enough away the parent couldn't be seen without advanced telescopes, and then life evolved on one of its planets.
That civilization would grow up in a world without stars. The sky at night would be pure black nothingness, except for the pinprick light of any other planets in the system. And then, after assuming their solar system was the entirety of existence for thousands of years, only in their culture's equivalent of the 1960s do they see the first light of other suns.
I seem to recall a few scifi stories with civilizations like that.
Hitchhiker's Guide had one that couldn't see the sky, I remember. So they developed without ever thinking of anything beyond them.