Purdue most certainly considers GPA! I don’t know who said that on your tour but that is false.
Per the common data set - GPA (HS transcript), Class Rigor, and Essay are the three most considered data points. https://www.purdue.edu/idata/wp-content/uploads/2025/06/CDS_2024-2025.pdf Section C7
Standardize test scores, APs included, are “Important”.
Northwestern should be moved into your reach category!