It is important to acknowledge that achieving a complete 100% view of the customer journey before conversion is unlikely due to certain limitations. For example, there are certain touchpoints (print, out of home, ...) that are untraceable and people use several devices/browsers without always being logged in, making it impossible to connect every dot.
Nonetheless, we can improve our worldview by combining different sources such as web analytics data, Meta ads, Google Ads, DV360, Microsoft ads, and marketing automation tools in a marketing data warehouse.
Based on this combined data set, we can create our own data-driven attribution model that acknowledges conversions connected to known marketing touchpoints. However, what about conversions in our CRM that we cannot trace because of user tracking consent for example? This can sometimes be a relatively big share of your conversions.
Ideally, we can also include these into our campaign evaluation to avoid undervaluing them. We can apply the same conversion and value distribution to attribute these "unknown" conversions based on the insights gained from the "known" dataset.
While this approach is still imperfect, it is better than ignoring 20% of your conversions/revenue. This is also similar to Google Analytics' "Consent Mode", only it happens outsides of GA, considering more data sources.