Where to find script for online store

Hello
I'm looking for a script for my website. Script for selling online items (actually information from .txt file)
It have to works like: I have 100 lines in txt file and the customer can see this stock on the website
He can buy from 1 to 100 lines (depends from stock)
If the item is not available, the customer should see "out of stock" and have no possibility to buy it
Will be good, if payment methods like paypal and crypto will be also included.

Where I can find something like this?

Just fill it in yourself, it's much easier.
You can use free open source software like opencart

I already have website on other CMS

Cant woocommerce improt data from file?

You might be able to use a platform like Shoppy