a thing that might be useful in this space is anonymous lists.
For the use case where a user wants to make a list to block or mute groups they’d be worried about retaliation from. Even if this behavior is banned by ToC, it’d reduce moderation burden if the retaliation is impossible in the first place.
an alternative for this: use an organization or alt account to create the list
I’d imagine some flavor of anonymously publishable content to be useful in the context of private data still, even if this is not the correct use case.