Honestly, I don’t think it’s a good idea to say that fediverse == activitypub in the first place.
IMHO all services that work in an open federated manner based on open federation standards are part of the Fediverse. Whether that protocol is AP, Matrix, XMPP or, yes, even Email; it’s all open standards where instances openly federate with other instances that implement the same standard.
Hell, we could even bridge between protocols. Not saying it should but if Lemmy had a mailing list bridge, would you consider someone replying to Lemmy emails from their self-hosted email server as not being part of the fediverse?
For the same reason I don’t consider AT to be part of the fediverse because it doesn’t operate in a federated manner as control is entirely centralised.
Oracle ZFS is so obscure by now that it’s irrelevant.
As usual with Oracle products, it’s just a means to squeeze poorly led companies.