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
