I have a ton of experience with this, and various systems, but here's how I recommend you go about this, as a strategy:

1. Get some cheap handheld barcode scanners such these:
   1. https://www.amazon.com/Portable-Handheld-Bluetooth-Wireless-QRbarcode/dp/B086YHQ7H4/
   2. https://www.amazon.com/Portable-Handheld-Bluetooth-Wireless-QRbarcode/dp/B08XQ1NXP1/
   3. https://www.amazon.com/Bluetooth-Wireless-Barcode-Portable-Handheld/dp/B07RL28JLF/
2. Create a spreadsheet, I prefer Google Docs but if you want to be fully offline, you can use any spreadsheet software. If you have a Mac, then Numbers comes free with your Mac. If you're on Windows or Linux you can use LibreOffice or if you want to spend money you can buy Microsoft Office.
3. Your scanner comes with a sheet with various barcodes that configure the device. You can scan them one after the other to set it up properly. What you do is have it press Enter or Tab after it's done scanning. This way when you scan a barcode or QR code, it types it into the keyboard and moves to the next field automatically.

Spreadsheet software is extremely sophisticated these days. You can literally write code to do some incredible stuff. The reason I like the online versions such as Google Sheets is how it keeps a revision history of all of your changes. This means you don't have to worry about backing up, and if you've made a mistake at some point, you can trace back. If there are several people working on the same sheet, you can easily find out who added/modified/removed something. They made a mistake? No problem, you can roll back to before their changes! Easy peasy. And it's also automatically multi-user, you can see other people doing stuff live in the system. And you don't have to deal with multiple versions of a file (who has the latest?!), with online collaborative sheets everybody's on the same document, it's always the same document, and you don't have to think about it at all. It's also absolutely free!

Tip 1: Put your formulas at the top of the sheet, so you can have as much space as you need below for your items.

Tip 2: You can program it to automatically move items between different sheets of the same document, depending on status. If you need to be alerted on items that drop below a certain quantity, you can have a "Low items" sheet, which will show you only items from the main sheet where the quantity dropped below X. Either that, or you can use conditional formatting to make an entire line red if the quantity is below X.

Tip 3: You can actually connect Google Forms to your sheet, which means you can have a "simple" interface for intake, of people you don't want exposed to your sheet. Since the barcode scanner is essentially a "keyboard", you can scan any barcode or QR code into any field in the form.

Why like this?

I will preface by saying: You don't need a tank to kill a mosquito. I think in your case, simplicity trumps features.

There's a ton of systems out there. They all have different UI/UX and workflows, but in my experience it's always best to first figure out HOW you want to get things done. What are the workflows that work for you? You learn a lot about the process when you build it as I described above. You understand the difference between UPC codes used by manufacturers, and your own internal barcodes, and you learn strategies on storage/inventory, etc.

If you have any questions let me know!