This app was mentioned in 9 comments, with an average of 1.89 upvotes
I used this app to scan all of my boxes:
https://play.google.com/store/apps/details?id=com.maiko.scanpet
You can export to excel and compare to what you ordered. Only problem was that some of the bar codes don't encode the item number, so had to go back and check some things by hand. But overall I think the app saved some time. There must be something similar for iPhone if you're in the apple ecosystem.
It's not clear why you want to use a rpi, especially if the goal is to do the tracking via excel.
If you've got a PC with excel what I would do is use a cheap android phone and a barcode reader app (that just uses the phone's camera).
You could try searching for an inventory app with barcode scanning like this. I've never used one, but it might fit your needs.
You'll need to work out the best way for you but when a new photo is detected, you could use AutoVoice or Get Voice to record the description and condition of the item before amending it to the filename or logging it against the file name in a Google Sheets. This will save a huge amount of time when going through everything again when creating the listings.
If they have barcodes, you could look into using a wifi scanner to spreadsheet app like ScanPet.
Have you checked the play store? There's tons of apps that allow you to do this.
https://play.google.com/store/apps/details?id=com.maiko.scanpet
That app says it outputs as an excel file. Simply export or copy the information from that into a text doc.
I can't do this in Excel.
However, there are apps that can do this, and then export barcodes to an Excel file.
I have used "Barcode scanner & Inventory" and it works for my purposes of cataloging my library. Your mileage may differ, and you may wish to explore other apps.
Link: https://play.google.com/store/apps/details?id=com.maiko.scanpet&hl=en
Scanpet is the best for these kind of stuff