It seems it is no longer possible in the v2 API to do much of anything with deleted files. Their metadata entries contain no ID or revision information, they cannot be downloaded, their revisions cannot be listed, and deleted folders cannot have their contents listed even with the include_deleted option set to true.
Is there a workaround of any kind in the v2 API, short of restoring the files to undeleted status in the account (which would cause them to reappear on synced clients, etc., none of which is acceptable when trying to access and archive old content)?
Access to deleted files generally was possible in the v1 API. This is now a severe limitation to the possibility for archival automation.