App for scanning and packing fba shipments

I had to repack a shipment myself and it’s about 400 units with a variety of skus maybe over 30. Are there any apps that allow me to scan the barcodes and create a packing list in Amazon automatically? I’ve found generic barcode apps but nothing that allows me to define each box and associate the scanned products to that box.

How does everyone else do this? I’ve searched a bunch and haven’t found anything. I thought I’d find something that already exist. Hoping I’d get lucky and find something that generate the Amazon packing template but so far nothing.