Opportunity Product (Opportunity Line Items) roll up to custom fields on Opportunity object?

Question

I am given some requirements to create custom fields to make a copy of the data sources on the opportunity object on Salesforce.

Here is the full user story: Sales Reps choose a variety of products via the product related list on the Opportunity object. We would like to create a copy of what data sources they choose to live on the opportunity so that we can export to another application. How would you go about creating fields on the Opportunity page that consist of the data source names (Product name) and List Prices (product.list prices) that the sales rep has chosen?

My original thought is to create a formula field and lookup to OpportunityProducts.[Product Name] or the OpportunityProducts.[Price List]. However, this cannot be done because OpportunityProducts is a junction object and we can't reference cross objects.

Given that an opportunity can have many products, would the custom field have to be a multipicklist field/text area field? How would we make the price lists accoridngly to the product selected? Here are some Product & List Price Examples:

Product Name	List Prices
Product 1	$1,000
Product 2	$2,000
Product 3	$3,000
Product 4	$4,000

The ask, I found is somewhat similar to this post.

Answer 1

Rollup Summary fields are best used to get things like total quantity, average cost, and the like. They can't summarize data this way, so the alternative would be a trigger. However, it's far more efficient to simply have the external system perform a sub-query and get the information directly. This is almost always less development effort than to bundle the data in Salesforce just to have it reparsed in the external application.