> the federation of that massive amount of data and storage
I'm not sure what you mean by that but the media blobs (photos and videos) are not "federated" (i.e. passed around instances) most likely, but hosted in one place (the instance of the author) and referenced by their URL.
it varies by activitypub implementation. mastodon for example caches media per instance, pleroma simply hotlinks.
briefly searching through github issues, i believe pixelfed does not cache remote media. discussion on this issue about remote media cacheing seems to indicate that pixelfed only caches avatars https://github.com/pixelfed/pixelfed/issues/4571
Intuitively, it is unlikely there's 500K individual servers set up.
We can then also observe other comments clarifying that no, there aren't 500K instances.
The other comments provide...tweets? mastodons?...from the maintainer also clarify that in practice, there's 1 instance.
People are questioning how that will scale, and the tweet from the maintainer was cited as part of that because the content of the tweet is that tl;dr there's a $2,600 month gap between Patreon and hosting costs.
I'm not sure what you mean by that but the media blobs (photos and videos) are not "federated" (i.e. passed around instances) most likely, but hosted in one place (the instance of the author) and referenced by their URL.