> the prefix is an index to its disk block location

What? This is definitely not the case and can’t be because B-tree nodes change while UUIDs do not.

I didn’t mean that literally, but no longer editable. Was supposed to have “like” etc in there.

But UUIDv7 doesn’t change that at all. It doesn’t matter what flavor of UUID you choose. The ID is always “like” an index to a block in that you traverse the tree to find the node. What UUIDv7 does is improve some performance characteristics when creating new entries and potentially for caching.