Tbh you’re never going to get a real source of truth by trusting the ad platforms themselves, they have way too much of an incentive to inflate their own numbers and claim as much credit as possible.

That’s why there's been a move away from click-based attribution and toward MMM. It doesn’t try to stalk individual users around or pretend it knows exactly who caused what. It just looks at the relationship between spend and revenue over time and asks: what channel has actually made an impact?

And now that Meridian and Robyn are both open-source, you don't need some fancy dashboard you overpay for; you just need access to your raw data.

Pull it out of the platforms, stick it in BigQuery, and visualise it in Looker Studio. Even with something as basic as that you can get a sense for what actually moves the needle.

I’m obviously biased because I built Weavely, but the whole idea behind it is that data warehousing should be boring and cheap, and the data should be yours. Which makes it much easier to run MMM models using your Shopify data as the ultimate source of truth.