Now take note:
A world that met its end = Miyu-verse, i mean look at that huge amount of snow and the lack of people the world basically ended at that point
Born from the failed choices that humanity made = In this world, Pandora's box was not opened until Darius did, which is like centuries apart, it diverged into a different timeline. Opening Pandora's box was a huge disadvantage for the people living at that age yes, but benefitable to the upcoming generations since the challenges and death they experienced made them more intelligent.
Also Darius said this on Chapter 58.1
You might be familiar with that black hole in the sky, it indicates a singularity, so then it might be a singularity that reached it end therefore became a lostbelt? Also the word coordinate, we all know travelling between worlds needs you to have a fixed coordinate in order to travel there. Also "A world independent from human history" ? Isn't that basically what Pan human history means, if Darius is saying that the world beyond that is a Pan human history then what makes their world not part of that? Lostbelt? might be.
Also let's not forget, the Fate/kaleid collab with FGO, we all know that collabs inside Type-Moon are canons even though the timeline is messed up af, so they have a way of connecting to Grand Order verse as well.