Thank you for taking the time to answer. I hope you might be willing to clarify a bit more for me. By “window”, I meant just… having access to a remote community via an API gateway, I guess.

I was under the impression that if I try to subscribe to a remote community hosted on lemmy.world from vlemmy.net, that is simply registering the URL of that community into some local directory in my instance, not duplicating the entire community contents into vlemmy.net. And then when I view a thread in that remote community, I am just retrieving the thread data from the host server at lemmy.world straight to my browser, not loading some local duplicate of the thread from vlemmy.net. Seems like it would get out of sync quickly if we are all reading separate local copies of the original.

So based on your answer, I am still misunderstanding something. What is the purpose of all the duplication then? Is it just for local caching purposes? Does this not needlessly drive up the amount of traffic because each instance is frantically trying to keep up to date with every other instance, rather than just letting each instance handle the requests for its own communities?

Each instance would have to handle the replication and storage of the entire lemmyverse.

Do instances fully replicate and locally store remote subscribed communities? My understanding is they are still solely hosted on the original instance; subscribing just opens a window to the community by making your instance aware it exists.