How to track the first source of traffic in indirect purchases in Google Analytics?

Question

Conversion

Colleagues, hello everyone!
There was a very important question on tracking sales on the site.
We want to track sales based on the original traffic source. That is, what would the transaction be assigned to the source from which the user came for the first time.
Of course, there are assisted conversions in Google Analytics, but they have a problem:
1) An assisted conversion can be attributed to both the first and second traffic source in the path of the last one to which the conversion is assigned.
2) Also, we cannot see which traffic source for a certain associated conversion was the last one that sold the product.
I would like to know if there are any other solutions besides Google assisted conversions?
Maybe some cookie handlers?
In general, I will be glad to any information on this topic. If there is directly with implementation examples, it will be great.
Thanks in advance! :)

Answer 1

You can upload user behavior data on your site to Google BigQuery using owox
In GBQ, you will find the first session (and its source) of the user who made the transaction.
Reports can be built in Power BI or other visualizers.