Not sure if it's exactly the same, but I had to add a When notification arrives with <message>, do <action> event trigger in my Crank macOS app (https://lowtechguys.com/crank) so I can show you how to do it on macOS:

      HOURS=6
      EPOCH_DIFF=978307200
      SINCE=$(echo "$(date +%s) - $EPOCH_DIFF - $HOURS * 3600" | bc)

      sqlite3 ~/Library/Group\ Containers/group.com.apple.usernoted/db2/db \
        "SELECT r.delivered_date, COALESCE(a.identifier, 'unknown'), hex(r.data)
        FROM record r
        LEFT JOIN app a ON r.app_id = a.app_id
        WHERE r.delivered_date > $SINCE
        ORDER BY r.delivered_date ASC;" \
      | while IFS='|' read -r cfdate bundle hexdata; do
          date -r $(echo "$cfdate + $EPOCH_DIFF" | bc | cut -d. -f1) '+%Y-%m-%d %H:%M:%S'
          echo "  app: $bundle"
          echo "$hexdata" | xxd -r -p > /tmp/notif.plist
          plutil -p /tmp/notif.plist 2>/dev/null \
            | grep -E '"(titl|title|subt|subtitle|body|message)"' \
            | sed 's/^  */  /'
          echo "---"
      done

Basically, notifications are in an sqlite db at ~/Library/Group Containers/group.com.apple.usernoted/db2/db and are stored as plist blobs.

In recent years, filesystem paths for system services have started to converge for both macOS and iOS so I'm thinking with jailbreak you could get read access to that database and get the same data out of it.