This is a neat idea and I’m not sure it’s every been brought up here so I’d like to explore it.
If the fediverse is a database, it seems to be sharded but in a long tail distribution where each instance has admins whose resources are on the line.
This localized provision of resources is kind of neat because it leaves the trade-off between human (admin effort) and technical resources (storage and bandwidth) to each instance. Instead of a tragedy of the commons as with many fully-anonymous systems we start here from more of a private property model.
I actually wonder what an MVP AP-enabled database host would look like from an API perspective.