Interstate already tracks non-tagged data in the same way GA does.
The GA Model Comparison Tool is great for the basics but I'd hardly call it a comprehensive attribution solution for static models. Even if you import spend data (which you have to do manually), you can't get any sort of understanding of what payback periods actually were, just present day ROAS and how it differs by model. You also can't see revenue, spend, and # of attributed conversion in the same report, filtering is a pain, etc etc. It does the basics but not much else.
The GA Model Comparison Tool is great for the basics but I'd hardly call it a comprehensive attribution solution for static models. Even if you import spend data (which you have to do manually), you can't get any sort of understanding of what payback periods actually were, just present day ROAS and how it differs by model. You also can't see revenue, spend, and # of attributed conversion in the same report, filtering is a pain, etc etc. It does the basics but not much else.