With the shopping cart extension which you can activate in your FundraisingBox at "Settings > Extensions > Fundraising" you are able to handle charity shopping carts. Donations are enriched with a table that show the content of the cart then.
This shopping cart content is stored in a custom donation field. E.g. you can create a custom donation field (type of this field should be "text") and call it "Shopping cart" or any other name you like. Select this field for the shopping cart in the extension settings mentioned above.
If you don't want to use simpleCart(js) you can create a charity shop for your own. Feel free do do anything you like with any kind of technology use would like to use. In the end you should transfer the shopping cart content to your donation form in a defined json format. Just prepopulate the hidden custom donation field with this json to show the cart content in a well formated table in your FundraisingBox. You can find more details under "JSON format for shopping cart data".