There is an example in the pistsuper manpage that uses "postqueue -j | jq" to select messages, and to feed a list of queue IDS into the postsuper command.
Untested example: postqueue -j | jq -r ' # See JSON OBJECT FORMAT section in the postqueue(1) manpage select(.queue_name == "deferred") | .queue_id ' | postsuper -h - Wietse